{"Input string was not in a correct format."} Plug-in creation error,

Question

using Microsoft.Xrm.Sdk;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Runtime.Serialization.Json;
using System.Text;
using System.Threading.Tasks;
using System.Web.Script.Serialization;

namespace LeadwayCIVUATPlugins
{
    public class TurnquestAgentCreatorPlugin : IPlugin
    {
        private static string DateFormat = "yyyy-MM-dd";

        private static string ValueForAttribute(string attributeName, Entity entity)
        {
            if (entity.Contains(attributeName))
            {



                if (attributeName == "new_typedecompte")
                {
                    object value = entity.Attributes[attributeName];
                    if (value != null)
                    {
                        OptionSetValue osValue = (OptionSetValue)value;
                        switch (osValue.Value)
                        {
                            case 2: return "2";
                            case 3: return "3";
                            case 40: return "40";

                        }
                    }
                }

                if (attributeName == "new_bifurquer2")
                {
                    object value = entity.Attributes[attributeName];
                    if (value != null)
                    {
                        OptionSetValue osValue = (OptionSetValue)value;
                        switch (osValue.Value)
                        {
                            
                            case 284: return "MARCORY";
                            case 285: return "PLATEAU";
                            case 286: return "VALLON";
                            case 287: return "YOPOUGON";
                            case 288: return "CORPORATE OFFICE";
                            default: return "Unknown Option";
                           

                        }
                    }
                   
                } // return entity.Attributes[attributeName].ToString();
                if (entity.Attributes.Contains(attributeName) && entity.Attributes[attributeName] != null)
                {
                    return entity.Attributes[attributeName].ToString();
                }
                else
                {
                    return "Attribute value is null";
                }
            }

            return null;
        }

        public void Execute(IServiceProvider serviceProvider)
        {
            // Obtain the execution context from the service provider.
            Microsoft.Xrm.Sdk.IPluginExecutionContext context = (Microsoft.Xrm.Sdk.IPluginExecutionContext)
                serviceProvider.GetService(typeof(Microsoft.Xrm.Sdk.IPluginExecutionContext));

            // The InputParameters collection contains all the data passed in the message request.
            if (context.InputParameters.Contains("Target") &&
                context.InputParameters["Target"] is Entity)
            {
                // Obtain the target entity from the input parameters.
                Entity entity = (Entity)context.InputParameters["Target"];

                // Verify that the target entity represents an account or contact.
                // If not, this plug-in was not registered correctly.
                if (entity.LogicalName == "new_intermdiaire" || entity.LogicalName == "new_franchise")
                {
                    try
                    {
                        // Create the turnquest client model based on the entity attributes

                        DateTime now = DateTime.Now;
                        AgentPayload agent = new AgentPayload();
                        agent.accountTypeCode = int.Parse(ValueForAttribute("new_typedecompte", entity).ToString());
                        agent.branchCode = int.Parse(ValueForAttribute("new_bifurquer2", entity).ToString()); // get dob from entity.attributes                       
                        agent.emailAddress = ValueForAttribute("new_email", entity); // placeholder
                        agent.name = ValueForAttribute("new_name", entity);
                        agent.status = "ACTIVE";
                        agent.shortDescription = ValueForAttribute("new_crmid", entity); // crm id entity.Attributes["new_crmid"].ToString();//
                        agent.physicalAddress = ValueForAttribute("new_adresse", entity);
                        agent.postalAddress = ValueForAttribute("new_adresse", entity);
                        agent.code = null;
                        agent.webAddress = ValueForAttribute("new_siteweb", entity);
                        agent.telephone1 = ValueForAttribute("new_mobile", entity); // mobile phone
                        agent.contactPerson = ValueForAttribute("new_personnedecontact", entity); // last name   
                        agent.contactTitle = "7914";
                        agent.pin = "0000";
                        agent.licenseNumber = ValueForAttribute("new_crmid", entity);
                        agent.statusEffectiveDate = now.ToString(DateFormat);

                        string json = new JavaScriptSerializer().Serialize(agent);
                        byte[] bytes = Encoding.UTF8.GetBytes(json);

                        // Send the create request to Turnquest
                        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Configuration.RequestUrl);
                        //using (System.IO.MemoryStream serializeStream = new System.IO.MemoryStream())
                        //{
                        //    DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(LagosReferrerObject));
                        //    serializer.WriteObject(serializeStream, obj);
                        //    postData = Encoding.Default.GetString(serializeStream.ToArray());
                        //    ///  return jsonString;
                        //}
                        request.ContentType = "application/json; encoding='utf-8'";
                        request.Accept = "application/json";
                        request.Headers.Add("Authorization", "46ea21639fb86ffb571a67fd348666f7067bf3c101924be1ea703dffcfb9c27ce3c4cfc88f29ee20bc23d8f7e5045dd0155acc87e19bc1dca41597b967e2a95f");//46ea21639fb86ffb571a67fd348666f7067bf3c101924be1ea703dffcfb9c27ce3c4cfc88f29ee20bc23d8f7e5045dd0155acc87e19bc1dca41597b967e2a95f
                                                                                                                                                                                                 //46ea21639fb86ffb571a67fd348666f7067bf3c101924be1ea703dffcfb9c27ce3c4cfc88f29ee20bc23d8f7e5045dd0155acc87e19bc1dca41597b967e2a95f
                        request.ContentLength = bytes.Length;
                        request.Method = "POST";

                        using (Stream stream = request.GetRequestStream())
                        {
                            stream.Write(bytes, 0, bytes.Length);
                        }

                        using (WebResponse response = request.GetResponse())
                        {
                            using (StreamReader rd = new StreamReader(response.GetResponseStream()))
                            {
                                string jsonResponse = rd.ReadToEnd();
                                JavaScriptSerializer result = new JavaScriptSerializer();
                                AgentRootObject obj = new AgentRootObject();
                                obj = result.Deserialize<AgentRootObject>(jsonResponse);
                                ;
                                //result.code
                                if (string.IsNullOrEmpty(obj.payload.code.ToString()))
                                {
                                    throw new Exception(string.Format("No agent code was returned from Turnquest.\nJSON response: {0}", jsonResponse));
                                }

                                entity.Attributes.Add("new_tqid", obj.payload.code.ToString());
                            }
                        }
                    }
                    catch (WebException ex)
                    {
                        using (WebResponse response = ex.Response)
                        {
                            using (StreamReader rd = new StreamReader(response.GetResponseStream()))
                            {
                                string errorResponse = rd.ReadToEnd();
                                throw new InvalidPluginExecutionException(string.Format("The Turnquest request failed with the response:\n{0}", errorResponse + " | " + ex.Message), ex);
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        throw new InvalidPluginExecutionException(string.Format("A new CRM ID could not be generated: {0}\n{1}", ex.InnerException.Message, ex.StackTrace), ex);
                    }
                }
            }
        }

        private class Configuration
        {
            public static string RequestUrl = "http://172.20.90.139:9095/agents/v1/createUpdateAgent";//"http://172.20.90.131:9092/agents/v1/createUpdateAgent";
        }
        //
    }
}