In your C ADK files VCSDK_Picture.h and VCSDK_String.h are malformed.
Opening
#ifdef __cplusplus
extern "C"
{
#endif // __cplusplus
is matched by
#ifdef VCSDK_PROJECT
};
#endif // VCSDK_PROJECT
which is incorrect.
I also posted some additional question in SQLite Server (discussion) about support for it in your C ADK.
Best regards from Sweden
/Chris