This message is displayed when the Player has attempted to play a file that is not a valid RealAudio or RealVideo file type. The RealAudio Player can only play .ra or .ram files; the RealPlayer can only play .rm, .ra or .ram files.

To make sure that your Player is working correctly, try playing the thankyou file that comes with the Player software. If it plays without trouble, the original file in question is probably not a .ra or .rm file.