unknown document
 

I have iTunes, and I was trying to launch a song to listen to it, but it did not work. I went to the library and tried to open it straight from the file, and it said: "the document could not be opened because the application program that created it could not be found. Could not find translation extention with appropriate translators." What should I do to get the songs to play at all, and to play through iTunes? I tried unistalling and reinstalling and it didn;t work, and I tried pressing shift+opt. and clicking on the file, but it did not work. I have an iBook, with Mac OS 9.1