What version of Premiere Elements are you using and on what computer operating system is it running?
Is this .m4a soundtrack from iTunes?
If so, you might be better served converting it to .wav in iTunes.
Are you new to the use of the Audio Mixer? If so, the following Adobe link may be helpful
Also, were you aware that 0 db represents the original level of the recorded sound and not no sound. If so, what are you trying to do - selectively mute the volume to accommodate narration? If so, have you looked at Smart Mix for that purpose?
Yes - from iTunes.
You are completely right - convertinbg to .wav solves the problem.
Thank you very much!!
Thank you for your great news of success. Great job.
We are glad for the opportunity to be of assistance.
Continued success and best wishes