Had a pick-up gig for a hour slot in a worship gathering. We rehearsed the stuff getting the turnarounds, took notes on charts; good to go....At the gig, every note I played was wrong, the guitarist had a puzzled look, staring at his fret board. We were supposed to follow the keyboardist, but she didn't know that the previous group had changed the transposition on the keyboard. Ended up transposing the whole set on the fly, was tough for the 1st couple of tunes.