There is a static library A with c++ classes wrapped by a C API in VS6. I developed a static library B in VS6 using callbacks from library A. The library B is used by the program C (commercial software) as a "user defined library" and linked to produce the program D. Questions: 1) When program C uses VS 6 it works, should it work fine with VS 2008? Because it doesn't. 2) When I tried to recompile library B in VS 2008 it gave me a .lib file with only 28KB, and the old one had more than 2MB. Is it ok? What Am I probably doing wrong? Thanks in advance