Are the VCX files compiled into the APP/EXE, or are they kept as external files? If they've been built into the APP/EXE, you have to be careful about references to the VCX (or any classes contained within it) as they are only available within the context of the APP/EXE. This is different from classes that were created using DEFINE CLASS ... ENDDEFINE, can be made available beyond APP/EXE boundaries.