multiple tracks not lining up when exported and then re-imported

My brother has Sonar LE - records guitar and bass tracks in a "Project format" where all the wav files (tracks) are stored in the audio folder specific to the Project. All tracks are synced in his Project file when opened. When he sends the individual wav files to me (I have Sonar Producer 6 and Studio One Artist) whether they are the wav files from the audio folder or wav files created for each track using the file/export/audio commands - and I import them the tracks are never lined up (synced). I've used this procedure many times and it has always worked without a problem from Producer 6 to Studio One Artist. Sonar LE doesn't seem to take into account any "space" on a track that begins later in a song. Any ideas? Thanks in Advance.

Bingo!!!! Exporting as Broadcast Wave files from Sonar LE worked like a charm!!! I was always using the riff wave format instead, which worked in Sonar Producer 6 for some reason. Imported the tracks into Studio One Artist and all of them lined up and were in sync!! Thanks so much!!