Charlie Austin scored the only goal of the game at The Valley and Powell was left scratching his head as to where they went wrong.
"We should have got something from the game," he said.
"We asked questions of them but they answered them. Our supporters have been terrific and in some ways we don't deserve it because of how bad we have been.
"This is a crucial week coming up for up with the trips to Peterborough and Huddersfield. We need to pick up something from those games.
"You have to remain positive and look upwards but I always knew this year would be tough for us getting used to the step up in quality.
"We need to make sure we are a Championship side next season."