"You have got to be disappointed - that is not what you want to happen on the first day of the season," said Cooper.
"I told the players if they give me honesty and endeavour I will take that all day long. We made mistakes at both ends of the field so we have to move on.
"It's the first game of 46 and we have had a kick up the backside. We prepared as well as we possibly could.
"Looking back is no good, we have to prepare ourselves for our next game at Nottingham Forest in the Capital One Cup on Tuesday.
"Everybody makes mistakes, in football and outside the game. When you make mistakes it's all about how you react and I'll be looking for the players to react in a positive manner.
"They should forget about this game once they have thought about what they did right and what they did wrong."