Accessing VISUAL FOXPRO DLL from .NET

I have Create simple Multithreaded from Visual FoxPro and Register on my workstation

then build one Web service in .NET to access the VFP DLL

 I received he following Exception

on 2nd line below:

   Dim service AsNewtestagentwebservice.testagentwebservice()

　　　　　　　　　　　 strRetdata = service.TestMethod("HELLO")

then, I create a console .NET application and used the same code above and get a different Exception