using a MATLAB .dll in C++ makes some trouble, because when including necessary header files, the mx-API fcns behaviour (??)

Hi,

i have quite a general problem with a MATLAB .dll. Is it possible that when including a MATLAB compiler generated .dll in C++ code, the mx-functions (that are also called in that C++ program) change there behaviour ?

What i have witnessed is that if i have a program using the mx-API to create datastructures, it all works as expected. I can call the mx functions and they work as described.

Now i added a MATLAB .dll to the project, and included the headers necessary, and it seems that now all the mx-functions get exchanged. Anyway, they do not work anymore, but only return NULL pointers. Can anybody please tell me why that happens and how to solve that ?

Any hint would help me a lot i think, as by now i am completely baffled and don't know any further.

Thanks a lot for reading so far, ...