ARE You Listening?
If you find yourself getting off rhythm when playing with a jam track or band, you're too focused on what YOU'RE playing and not listening to the band. If you know the piece well enough to play to accompaniment, you know it well enough to focus your attention on the band and how you're fitting in time with them. If you're not SURE where you need to be in time in relation to the band, I recommend highlighting the downbeat notes of each chord change (downbeats of bars 1, 5, 7, 9 and 11 should do)... this gives you target points reference.