VB reports bad calling convention from C DLL

My C++ DLL has two functions, one is purely for testing and takes no parameters(just pops up a MessageBox), it works fine. The other takes a string (LPCSTR) as a parameter.
My problem is that when I use the second function from my VB app I get the Bad Callling Convention problem. I know there is lots of docs on this and Ive read a good deal of them but I still cant resolve the issue. / This is an example of an exported variable


Also: Using VC++ 6.0 (so no .DEF ffiles)
Some code...(DLL)

extern "C" DEERSDLL_API int testDeersdll()
{
    MessageBox(NULL, "hello world","hello world",MB_OK | MB_ICONINFORMATION);
      return 7;
}
// This is an example of an exported function.
extern "C" DEERSDLL_API int  fnDeersdll(LPCSTR argv)
{
   ...my code here
}

Some more Code...(VB)

Declare Function fnDeersdll _
Lib "D:\vs\MSDev98\MyProjects\deersdll\Debug\deersdll.dll" _
(ByVal ssn As String) As Long


Declare Function testDeersdll _
Lib "D:\vs\MSDev98\MyProjects\deersdll\Debug\deersdll.dll" _
() As Long

______________________________
Ive used dumpbin to check the exported names and everything matches up.
Im using ByVal in my function as the docs claim that VB actually passes a ptr when you pass byVal which is my intention (Read that passing by ref actually passes a ptr to a ptr meaning Id have to use a LPCSTR *.

Thanks for any help you can provide....
BTW: I thought about putting the __stdcall MACRO in my function header in case it was a stack problem(saw one answer where this was suggested, but it remangled my names and most of the examples on MSDN dont use that macro).