Rotherham boss Andy Scott felt his side's failure to defend set-pieces cost them in the 3-2 defeat at Dagenham & Redbridge.
Danny Harrison volleyed in the opening goal for the Millers after 29 minutes, but the Daggers turned the game around when Jon Nurse headed in after 50 minutes and Abu Ogogo's shot deflected in off Mark Bradley 12 minutes later.
The Millers levelled almost immediately through Alex Revell, but Scott Doe headed in Cristian Montano's corner at the near post in the 79th minute to win it for Dagenham.
Scott said: "When you concede goals from set-pieces as easily as that you've got no chance. Especially against Dagenham, who chucked everything at us. We knew they would pump balls into the box and make it hard, we should have dealt with it.
"There was a 15-minute spell in the game where we haven't performed very well and it cost us the game. If you look at the whole game we've had more chances than we've had in two or three games and really good chances, one-on-ones or shots in front of goal.
"It didn't go in for us, but we knew that at half-time if we could perform the same again we'd win. It's difficult to put your finger on it, but we showed in the first half, and at times in the second half, we should have won this game comfortably."