VB.net Getworkitemsasync

Question

I'm trying to fetch all work items below is my code - I get an exception Exception thrown: 'Microsoft.VisualStudio.Services.WebApi.VssServiceResponseException' in System.Private.CoreLib.dll

    Public Async Function PopulateWITs As List(Of Integer)) As Task(Of Integer)

        For i = 0 To workitemslist.Count - 1
            Dim wid = Await WitClient.GetWorkItemsAsync(workitemslist, WorkItemFields, queryResults.AsOf).ConfigureAwait(False)
            Stop

        Next