Compilers will decorate function names based on linkage, calling convention, and whatever else (it's all compiler dependent) - Stdcall and DLL tools of MSVC and MinGW
VB[A] wants stdcall but with no decoration (same as most all Win32 API DLL's). The normal way to achieve that is with a DEF file. "--add-stdcall-alias" allows you to skip using a DEF file.
>> Now I'm going back to the old BSTR problem
Does the code from post #11 work?