Sound end earlier than clip

Hi! I have a problem with my flash intro. When I try to put a sound as a BGM for my flash intro, the sound end earlier than the flash clip. My intro clip is 805 frames and 30fps. My intro is 29.5 sec and i have the sound file about the same length. When I try play the clip, the sound end first. So I’m looking for help to make the sound file end same time with the clip. If anybody out there know solution about this problem, please help me. Thanks in advance for your help.