He said: "Raphael did very well on his debut against one of the best teams in League One and I feel sorry for him about the penalty.
"I have checked on the DVD and he clearly played the ball. I'm very disappointed with the decision.
"It would have been easy for the lads to feel down after falling 2-0 behind but we responded very well and had a real go at Peterborough.
"We are conceding too many goals which are coming too easy to our opponents. We need to shore things up."