decompress avi files with visual C++

I can read the avi files from a Sony dv camcorder (vids = dvsd) but AVIStreamGetFrameOpen returns a NULL and ICDecompressQuery also fails. I have qdv.dll on my system. How do I get Visual C++ to recognize the codec so these two will work? Visual C++ .NET under XP pro. Thanks,

The frames are coming out of the SampleGrab compressed and sending it as is to the VideoRenderer. I need to know why ? and how do I fix it. When my program captures a fram from the buffer, it is saved as a bmp of 112kb but windows can’t read it.

This is well beyond the scope of this site. You may want to ask at doom9.org, since they have more expertise at the programming end of things.
Now this is from someone who knows little or nothing or programming (but a little about codecs): I looked at http://msdn2.microsoft.com/en-us/library/ms706732.aspx and it lists vfw.h and vfw32.lib as libraries and header files for AVIStreamGetFrameOpen. VfW stands for Video for Windows. Now Microsoft’s DV decoder (qdv.dll) is a DirectShow decoder. Could that be the reason?