What version of Premiere Elements and on what computer operating system is it running?
Classically Premiere Elements has problems with iTunes music. The answer is to convert the iTunes music to WAV version in iTunes, and then import the iTunes WAV version export into the Premiere Elements project with Premiere Elements' Add Media (Get Media)/Files and Folders. More version specific information once you post that version information.
Please see iTunes conversion details...
Any questions or need clarification, please do not hesitate to ask.