The Swansea City manager told the official website "To control the game like we did and not come away with anything is so frustrating,'' declared Brendan, "especially as we lost to a penalty that never was.
"It was not a penalty. I've watched it over and over in the dressing room and Alan Tate clearly takes the ball.
"I had a good chat to the referee after the game, but he wanted to see it again before holding his hands up.
"But it doesn't take away from the fact that we got undone by a decision that was not good.''
But despite the defeat, the Swansea manager was still pleased with the performance against a side fighting for their lives.
"I'm very proud of my players,'' he added. "Everyone kept saying that the pitch is unplayable at times, but we passed the ball well and made it playable.
"With 11 games to go we can't afford to dwell on setbacks. We've got to dust ourselves down and go again on Tuesday night against Watford at the Liberty.
"There are going to plenty more twists and turns to come between now and the end of the season.''