Paul McGuinness was disappointed that United's Under-18s couldn't make their possession count as the Reds crashed of the FA Youth Cup on Wednesday.
The Reds went two goals down to Carlisle before pulling one back before half time. But they couldn't turn their dominant possession into the crucial equalising goal in the second half.
"You have to give credit to opposition, they deserved to go through," the U18s boss told MUTV. "We didn't take advantage of our possession. And to have the chances we had and not to take them wasn't good enough.
"We made basic mistakes in the build-up to Carlisle's goals. We played some good football after that, but we didn't carry that into the second half. We didn't test the goalkeeper enough.
"We had loads of possession and even played some good passing football, but we were too narrow. We didn't use the width well enough and didn't get enough crosses in."
McGuinness says his young players have passed up a big chance to impress on youth football's biggest stage.
"The defeat puts us back two steps," he added. "We've missed an opportunity to do well in this competition. The players now have to lift themselves. It's a big defeat and at this club sometimes that's a burden you have to carry."