folks,

i am trying to implement an example choreography between two workflows based on web services. the simple - asynchronous (just one-way calls) - choreography should execute as follows:

• the Initiator calls FunctionA of the Responder using an InvokeWebService activity
• the Responder receives the message via a WebServiceInput activity
• the Responder does some simple processing
• the Responder calls FunctionB of the Initiator using an InvokeWebService activity
• the Initiator receives the message via a WebServiceInput activity

however, when the Responder calls FunctionB the Responder's workflow throws an InvalidOperationException (please see the full stacktrace below)

System.InvalidOperationException occurred
Message="Current session has no workflow instance associated with it. Send activation message to start new instance in current session."
Source="System.Workflow.Activities"
StackTrace:
bei System.Workflow.Activities.WorkflowWebService.GetWorkflowInstanceId(Boolean& isActivation)
bei System.Workflow.Activities.WorkflowWebService.Invoke(Type interfaceType, String methodName, Boolean isActivation, Object[] parameters)
bei Initiator.Workflow1_WebService.FunctionB(String arg) in C:\...\qklkmprz.cs:Zeile 39.
Both workflows are hosted in the ASP.NET development server environment and make use of the SQLPersistenceService

any help would be highly appreciated :-)

thanks in advance,

marco