DotnetExtensionReplay.dll: System Exceptions: Uknown

Hi,

We have added some C# code in the v_userinit section after recording our  .NET application.  Compilation gives no error. 

Added code in v_userinit (LR 11.52 .NET 4)

          lr.log("=== Start code to initialize CDA ===");
       
             lr.log("=== Create new session");
         Session = new CDASession("PerfTest");
             lr.log("=== Configure new session");      
             Session.Configure(@"D:\appl\SalesApp.L\SalesApp\CDAConfig\CdaConfig.xml");
         
          lr.log("=== End of code to initialize CDA ===");      

But during replaying we get next error :

Virtual User Script started at : 10/02/2014 14:42:27
Starting action vuser_init.
=== Start code to initialize CDA ===
=== Create new session
=== Configure new session
Error: An exception was raised while calling invocation function in interpreter extension DotnetExtensionReplay.dll: System Exceptions: Uknown.
Action was aborted.

Any idea ?

Thanks in advance,

Peter