Please help.  I've been stuck on this for days.  I have a sample web service, written in C# that I'd like to have be able to call into a DLL written in C++ (also in the .NET Studio).  I can compile and build both pieces, but I'll be hanged if I can get the call to work at run-time.

My service code (snippet) looks like this:

 public class Service1 : System.Web.Services.WebService
 {

    [DllImport
        (
        "C:\\MyThunk\\Debug\\MyThunk.dll",
        EntryPoint="MyDocThunk",
        ExactSpelling=false,
        SetLastError=true,
        CharSet = CharSet.Unicode
        )]

    static extern int
    MyDocThunk
        (
        [MarshalAs(UnmanagedType.LPWStr)]string aString,
        [MarshalAs(UnmanagedType.LPWStr)]string anotherString,
                );

...

    string    astring1;
    string astring2;

    // call the imported fn():

    Service1.MyDocThunk( astring1, astring2 );

...
}

My DLL code (snippet) looks like:

extern int  __declspec( dllexport)  
MyDocThunk
    (
    WCHAR    *string1,
    WCHAR    *string1
    )
{
    AFX_MANAGE_STATE(AfxGetStaticModuleState());

    // normal function body here

    CString    myWorkString;

    // ignoring the bloody inputs for now...

    return 0;
}

The DLL is  build __stdcall so as to mate up with what I understand is the default .NET behavior for DllImport.

I can put a breakpoint on the call to MyDocThunk in the web service and I hit it.  If I try to continue, or step in, I don't get an exception, but IE pops back up claiming that the web page cannot be found (an HTTP 500 Infernal server error).   Of course, if I remove the external call, then my simple Web service operates as expected.  I really need to be able to "thunk" out to an unmanaged DLL (for reasons I won't go into here).

I admit I'm a newbie at C# and .NET, but the total lack of error info and what seems to be a fairly simple call failing is frustrating, to say the least.

I've even tried doing the DllImport as an ordinal to avoid name mangling issues.  No dice.  Something so simple should not be so hard (and the error info so well hidden).  WTFO!

Can someone point at what I'm doing wrong?

TIA,
Bill