Rochdale can forget about reaching the play-offs unless they improve, according to manager John Coleman.
Medy Elito's winning goal in the third minute of stoppage-time gave Dagenham & Redbridge a 2-1 victory.
Andrew Tutte had put Dale in front in the 72nd minute before Abu Ogogo levelled three minutes later.
Coleman cut a frustrated figure after he presided over a third straight defeat.
He said: "It's a blow for us, of course. We'd worked on one or two things in training but unfortunately some of the players just didn't carry the necessary instructions out when it came to match day.
"That's been happening just a little too often lately and it's something we really need to try and drum into them.
"It's going to be a difficult run-in to the end of the season.
"Our fans have seen some decent stuff at times this season, but it's got to get better.
"Somehow we seemed to be missing that cutting edge and when you're in a situation such as ours we need to pick it up.
"There's been talk of a push for the play-offs but on this evidence we've got no chance."