Audya Problem Dual Mp3 sometimes start only the 1.

hi all, I play with styles but some times need in pause to use mp3 and cross them. Usually I play mp3 with first player, then listen with second (mp3sfx) thourgh 3.output another and when ready press Enter, then start the second, I cross them through the cursor and fade out the first though cursor. normal like dj

Problem is that some times with some mp3 (usually are 128 ore 160kbs) when I press Enter (in mp3sfx) not start the second but stop the first and then start: the some mp3 don't want to start in the 2. mp3 player , it always go to the first player
that only for some mp3 not all
why ?