Michael Symes and James Ryan both struck on the counter-attack before Lee Hughes replied with a penalty late on.
It left Backe perplexed, and he said: "It was a completely different performance from the one we showed at Hereford a week ago. We looked nervy on the ball, had too many unforced errors and never looked like we were in the game for the whole 90 minutes.
"I'm struggling to put my finger on why we were so poor, especially because we had won three in a row coming into this game. How we then go from that to looking vulnerable again is a mystery.
"I'm disappointed because a win would have helped us close the gap on the top three, which is something we needed to do going into the Christmas period."