Hey,
what typ of music is it and is the file correct bpm analysed? The software can only helps you highlighning them but the computer system is not the best and not perfect
so check if the PBM and also the start point is set correctly that the song is analysed correct.
Second problem is when two songs have different BPMs it can slow down and speed up but not every song fits in the other song, special when you mix two genres together.
So give us an example like I want to mix two house songs one with 128PBM and one with 126 but it will not synced.
So what exactly is your problem there?
regards
Christian