eConnect.eConnectException: Sequence contains no elements

I have an application that syncs a document library on Sharepoint with KL using eConnect. Basically on a person approving a document, a work flow gets kicked of, and the workflow sends the invoice to GP2013. Seemingly randomly we are getting this error[1] when eConnectMethods.CreateTransactionEntity is called. After that when eConnectMethods.Dispose is called another error is thrown[2].

The frustrating thing about this error is if we rerun the workflow, it works no problems. Same code and same xml and the error seems to not follow any patterns.

[1]

CreateTransactionEntity eConnectException: Microsoft.Dynamics.GP.eConnect.eConnectException: Sequence contains no elements 
   at Microsoft.Dynamics.GP.eConnect.ServiceProxy.CreateTransactionEntity(String connectionString, String xml) 
   at Microsoft.Dynamics.GP.eConnect.eConnectMethods.EntityImportImplementation(String connectionString, String sXML, Boolean isTransaction) 
   at Microsoft.Dynamics.GP.eConnect.eConnectMethods.CreateTransactionEntity(String connec tionString, String sXML) 
   at Mysolution.namespace.SendToGreatPlains.submit(eConnectType eConnType, String dbConn, String& errorMessage) 

[2]

System.ServiceModel.CommunicationObjectFaultedException: The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication  because it is in the Faulted state. 
   at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout) 
   at System.ServiceModel.Channels.ServiceChannelFactory.OnClose(TimeSpan timeout) 
   at System.ServiceModel.Channels.ServiceChannelFactory.TypedServiceChannelFactory`1.OnClose(TimeSpan timeout) 
   at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout) 
   at System.ServiceModel.ChannelFactory.OnClose(TimeSpan timeout) 
   at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout) 
   at Microsoft.Dynamics.GP.eConnect.ServiceProxy.Dispose() 
   at Microsoft.Dynamics.GP.eConnect.eConnectMethods.Dispose() 
   at Mysolution.namespace.SendToGreatPlains.submit(eConnectTyp e eConnType, String dbConn, String& errorMessage) 

I've tried this article's suggestion:

http://support.microsoft.com/kb/2539263

I've also tried many changes in the code.

These are on on good hardware and the network between them is solid.

Any suggestions? Do you need more information?