Audition, exports fine but no sound when playing it in the program

Hi

I recently used Adobe Audition for recording and it seemed to work fine. The level bars? on the bottom and the sound waves looked ok to me. But when I played it I couldn't hear anything.

The exported file has no problem. It plays fine. And so does the computer's sound system. The only thing not working is the playing sounds in the program.

I also tried changing the output speaker in 'audio hardware' but there was only one speaker in option and so I couldnt change it.

Please help me...