Jos Luhukay says a sloppy five-minute period gifted Derby County victory over Sheffield Wednesday.
The Owls led against County through Adam Reach's early strike but County levelled through Harry Wilson before Jack Marriott scored the eventual winner.
It was a fifth defeat in six for Luhukay's side and afterwards the Dutchman says individual mistakes continue to cost his team.
"In five minutes we gave two goals away, down to individual mistakes," Luhukay said.
"Derby profitted from our mistakes and made it 1-1 and then 2-1.
"When you lose a game you are disappointed.
"We played very in the first 30 minutes and made a good goal from Adam.
"It was very good from us that first 30 minutes.
"We had some very good chances to make the second goal.
"I think Fernando Forestieri had maybe the best chance to make it 2-2 and Morgan Fox hit the post.
"These are maybe the moments where we can get back into the game.
"Derby were effective with their chances, they had three shots in the first half and scored two."
Luhukay says that errors from his players continue to frustrate him.
"It is very frustrating," added Luhukay.
"When we look back over the last six or seven games we give goals away easy.
"Teams with offensive quality profit from our mistakes.
"That has nothing to do with formations or tactics.
"You can not, on this level, give this (type of chances) away."