:confused: :confused: Is it possible to call an Extension DLL from VB as I've a satellite orbit prediction DLL that exports a C++ class only. The DLL will need to be integrated with Matlab eventually but I'm looking into this for a colleague and don't have Matlab on my PC, just Visual Studio. eg. #define DLLEXPORT __declspec(dllexport) class DLLEXPORT CSGP4_SDP4 { ...member functions here. } Any suggestions would be appreciated. Thanks Kaitain