Hello Cetin,

one cannot compile a mixed managed/unmanaged dll which calls into _fastcall methods - _fastcall is incompatible with the /CLR switch.
http://msdn2.microsoft.com/en-us/library/fb18b15e.aspx

And since all LCK functions and all selfwritten functions are declared with the fastcall calling convention, managed FLL's aren't possible.

If you just want to pass a few parameters to a C# class without using COM interop you can write a standard C DLL.

...
void _stdcall YourFunc(int someParam, char* someParam2)
{
// call C# code ..
}

yourproject.def file:
LIBRARY your.dll
EXPORTS
YourFunc

then use DECLARE in VFP.

Regards
Christian