Excel VBA: "Run-time error '49': Bad DLL calling convention" calling C++ dll

Question

I am attempting to call a C++ DLL from Excel-VBA.

I know the DLL function is being executed as I inserted fputs() logging calls to track execution and the stamps are showing up in my log file. The problem is, whenever the DLL function returns, I get Error 49.

Here is the declaration in VBA:

Private Declare Function InitMCR Lib "MCRBoilerplate.dll" Alias "?initMCR@@YGXXZ" ()

and here is the declaration in C++

__declspec(dllexport) void __stdcall initMCR() { ... }

Why am I getting this Error 49 behavior, even though the DLL calls appear to be working?

Answer 1

In VBA, functions that return void need to be declared as Sub instead of Function

So the declaration in VBA should be:

Private Declare Sub InitMCR Lib "MCRBoilerplate.dll" Alias "?initMCR@@YGXXZ" ()

See MSDN page on VBA Declare statement