Sync feature matching to the wrong part of the bar.!

I mix a lot using loops on the wave form, when using the sync feature pressing at beat 1 of 16 I can see it line up at the correct point and then it decides to move it 2 or 4 beats away from the correct point. This can be corrected sometimes using th cue point button but it can be really hit and miss. Is there a setting by which it syncs to the correct / closest beat ? I cannot understand why it does this. Please advise!