Kenny Jackett rued Pompey's lack of attacking threat in defeat to Blackpool.
The Blues fell to a dispiriting 2-0 loss to the Tangerines at Fratton Park with a performance which represented a low for the season.
Defensive mistakes proved costly in the defeat - but Jackett was frustrated by his side's firepower in the final third.
The Pompey boss said: 'The goals were poor to concede but I'm more frustrated about us as an attacking force.
'Christian (Burgess) elected to take the ball on his chest and through that touch, I presume, has played Vassell onside.
'The second goal was a little bit of a hashed clearance, but, even so, Robertson is still clear on the far post.
'It was a defensive display from Blackpool where they made fewer mistakes than us.
'The overriding frustration, though, is what we did with the ball and going forward. We didn't do enough.'