NEIL Harris said Millwall paid a heavy price for their missed opportunities after they were beaten 2-0 by Blackburn on Tuesday.
The Lions had 22 shots at Ewood Park but only six of them were on target, whereas Rudy Gestede and Jordan Rhodes made no mistake for the hosts with two late chances.
And Harris said: "I'm frustrated, definitely. Their two goal-scorers have scored more goals than my whole squad, so I think it's clear to see why they've won that game 2-0.
"We can talk about the positives, how good we were and how many chances we created, but ultimately to win games of football you have to score goals.
"The standard of this club is to be scoring goals and winning games.
"We've got plenty of spirit, togetherness, desire and ability in the squad but it doesn't change the result.
"I wouldn't say tonight sums up the season but the fact we haven't scored enough goals this season is clearly shown by where we are in the league.
"Defensively we've been terrific over the past few weeks but where we are in terms of taking our chances is what's costing us.
"It's been highlighted that we've been so solid and so reliable recently but we've not had the killer instinct in front of goal.
"I'm disappointed for the back four and the goalkeeper because they were fantastic – the whole team was outstanding, as were the subs.
"Their second goal came from us pushing forward but we didn't take our chances."
Defeat leaves Millwall in a perilous position with just two games left to play.
They are four points behind Rotherham, who now have a game in hand, although the Millers could yet face a deduction from the Football League.
And Harris hasn't given up hope of keeping the Lions in the Championship.
"Before tonight I thought we had to win two games to stay in the division, so my thoughts still haven't changed," he said.