"File Format cannot find MPEG file header. This may not be an MPEG file."

I get this message often when I finish extracting a bin/cue file into an mpeg and I try to play it on Realplayer. Some files I've extracted work fine but others I usually get this message. Is it the extraction program I'm using? Or maybe the file I've downloaded is corrupt? I use cdmage. Thanks for any help on this