First-half goals from Lee Miller and Brad Potts set up Carlisle's first double of the season and David Amoo's header just before the hour-mark proved to be the clincher against a Dons side that never really got into gear.
Robinson said: "The players let themselves down. Carlisle played well, but my players let themselves down and they know that.
"We have problems all over the park. Carlisle were the better team than us and I can only question the hunger and desire and they had more hunger and desire than us.
"We were the second best team in the league in December and the loss of four players is bound to have had an impact.
"We have lost some quality players and it's hard to replace them.
"The players on the pitch should have done better and I want to bring four players in.
"I will make mistakes, but my attitude won't be as bad as some of the players.
"Longy (Chris Long) looked a threat, but he was isolated on his own. Some may have played their last game for me."