Restore encryption key for dataware house

Question

After DW re-installation I tried to restore the encryption key as you can see in picture one.

In the next step I choose the backup encryption key and click forward, then it appears a dialog where I asked for if I want to override the existing file and I clicked yes (see picture 2).

Then I disabled job schedules via Get-SCDWJob | foreach-object { Disable-SCDWJobSchedule -JobName $_.Name } and register SM to DW. After awail I recognized that the MPSyncJob takes no progress. I unregister DW again and follow the troubleshooting article to recover the stucked job. But without any success and I run into the following error:

The System Center Data Access service failed due to an unhandled exception.    
The service will attempt to restart.   
Exception:   
  
Microsoft.EnterpriseManagement.ConfigurationReaderException: Funktion vom Typ "Microsoft.EnterpriseManagement.ServiceDataLayer.ISecureStorageManagerFeature, Microsoft.EnterpriseManagement.DataAccessService.Core, Version=7.0.5000.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" kann dem Container nicht hinzugefügt werden. ---> Microsoft.EnterpriseManagement.ComponentActivationException: Der Konstruktor für die Komponente hat eine Ausnahme zurückgegeben. Weitere Informationen finden Sie in der Beschreibung der eingeschlossenen Ausnahme. ---> System.Security.Cryptography.CryptographicException: Falscher Parameter.  
  
   bei System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr)  
   bei System.Security.Cryptography.RSACryptoServiceProvider.DecryptKey(SafeKeyHandle pKeyContext, Byte[] pbEncryptedKey, Int32 cbEncryptedKey, Boolean fOAEP, ObjectHandleOnStack ohRetDecryptedKey)  
   bei System.Security.Cryptography.RSACryptoServiceProvider.Decrypt(Byte[] rgb, Boolean fOAEP)  
   bei Microsoft.EnterpriseManagement.Security.AsymmetricKeyManager.Initialize(Byte[] publicKey)  
   bei Microsoft.EnterpriseManagement.Security.SecureStorageManager.Initialize()  
   bei Microsoft.EnterpriseManagement.ServiceDataLayer.SecureStorageManagerFeatureImplementation..ctor()  
   --- Ende der internen Ausnahmestapelüberwachung ---  
   bei Microsoft.EnterpriseManagement.ComponentActivator.Activate[T](ActivationContext`1 context)  
   bei Microsoft.EnterpriseManagement.SingletonLifetimeManager`1.GetComponent[K]()  
   bei Microsoft.EnterpriseManagement.FeatureContainer.GetFeatureInternal[T](Type type, String featureName)  
   bei Microsoft.EnterpriseManagement.FeatureContainer.AddFeatureInternal[T,V](ActivationContext`1 context, String featureName)  
   --- Ende der internen Ausnahmestapelüberwachung ---  
   bei Microsoft.EnterpriseManagement.ConfigurationReaderHelper.ReadFeatures(XPathNavigator navi, IContainer container)  
   bei Microsoft.EnterpriseManagement.ConfigurationReaderHelper.Process()  
   bei Microsoft.EnterpriseManagement.ServiceDataLayer.DispatcherService.Initialize(InProcEnterpriseManagementConnectionSettings configuration)  
   bei Microsoft.EnterpriseManagement.ServiceDataLayer.DispatcherService.InitializeRunner(Object state)  
   bei System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)  
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)  
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)  
   bei System.Threading.ThreadHelper.ThreadStart(Object obj)  

My question is, is this error related to the overridden encryption key? And why it asked me to override if I only want to restore the key?