I found the solution here:
Use a function from an external DLLStop using stdcall in your typedef. The lite-c compiler may not know any other callingconventions then cdecl so stack is cleaned up 2 times (by caller and callee) and will crash you.
Try cdecl.
before:
void WINAPI hellozorro(char*);
after:
void __cdecl hellozorro(char*);
This works like a charm.
Conclusion: WINAPI is defined as __stdcall in windows.h. stdcall is not compatible with my DLL for reasons unknown. Instead, use cdecl.