PRISM exception on not existing method

I am using PRISM for Silverlight 4.0 in one of my projects where I also access Sharepoint 2010.

The strange thing is that randomly I get the error:

An exception occurred while initializing module 'SharepointServi开发者_运维知识库ceModule'. - The exception message was: Die Methode add_GetListCompleted im Typ SharepointServiceModule.Services.SharepointObjectModelService der Assembly SharepointServiceModule, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null hat keine Implementierung. - The Assembly that the module was trying to be loaded from was:SharepointServiceModule, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null Check the InnerException property of the exception for more information. If the exception occurred while creating an object in a DI container, you can exception.GetRootException() to help locate the root cause of the problem.

Which is very strange for me because first of all it happens only randomly and second that the method "add_GetListCompleted" is an event which must be implemented because I use it and it works.

Does anybody have an idea of whats going on here?

I found a solution for my problem.

First I tried to change the name of the interface and I noticed that the interface name did not change in the error message.

Therefore I removed the affected xap module from the Web project (this can be done in the properties of the "name.Web" project under "Silverlight Applications") and added it again. Then I performed a clean of the solution and a rebuild. After that everthing worked fine...