Problem wirh creating OCX which links a library written in MFC

I used the source code downloaded from CodeGuru:
"bitmap & palettes"--->"MFC Class for BMP,JPEG,GIF" by Julian Smart
The Library uses the CObject calss as its base calss.
I called the functions of the library in an application which displays JPG, BMP and GIF images. It worked well in such a case.
However, when I used the same library in an OCX, it displays nothing but a black image.
Therefore, I suspect there could be some conflicts between MFC and OCX since the library uses some MFC stuff such as CObject.
The environment of my PC is NT(SP3) and VC6 version.
Does anyone know how to solve this problem?
Thank you very much for your help.