Need help on audio channels mix

  Hey, I'm pretty new to this and to not know all the proper terms. But I've been editing simple podcasts for about a year and haven't run into this problem before.

  When I went to start aditing my last podcast, I did everything normally. Created a project, drug my media into it, created a sequence, placed media in sequence, synchronized everything, and then opened the audio in Audition and did my normal editing on it. then I saved it and went back to Premiere. 

  But now for some reason my audio clips are only playing out of the left speaker, or the right speaker (depending on which track I place it in).

  Track A1 only plays out of the left speaker, and track A2 only plays out of the right speaker. It doesn't seem to matter what audio clip I place in those tracks, same results.

   Normally for me, in all the tracks, everything plays out of both speakers. And when I open the audio clips in audition, they play just fine.

  I'm sure that it's something simple and obvious, but it's had me stumped for several hours. Can anyone help?