What program are you using and how do you go about importing the files? Make sure that you locate and drag & drop the file from the media pool into the arrangement. If that doesn't work for a standard MP3 file, something with the codecs on your system might be a little messed-up. Depending on how tech-savvy you are, that's something you could possibly diagnose and rectify yourself or something that Magix support could help you with.