Problem Importing Audio

I've been using Adobe Audition for a while and have never had a problem.  Now it seems that when I try and import a file like a .mp3 or .wav it is only visible in the edit mode.  When I switch to the multitrack mode the files Iimported are not in the file window to the left.  So now I cannot drag and drop the audio files onto the multitrack window.  If someone could please help me fix the problem I would greatly appreciate it.

Try this before importing a file, start a new session in multitrack and save it. And also, check the bit-rate of the multitrack isn't different to the bit-rates of the files being imported. Not a guaranteed solution, just things I would try.

Thanks it worked and everything is operating fine.