GARY Rowett said his side "tried everything" to find a breakthrough against Birmingham but the Millwall boss admitted his side lacked a clinical edge in Wednesday's Den stalemate.
Lee Camp saved from Jed Wallace, Jayson Molumby and Jon Dadi Bodvarsson and the Lions' best chance came late on when substitute Tom Bradshaw just failed to reach Mahlon Romeo's low cross.
Blues' defender Kristian Pedersen shot past Bart Bialkowski in the 50th minute but the whistle had gone for a push on Jake Cooper by Harlee Dean.
"When a side like Birmingham come here they make it really difficult, the drop in and defend with lots of bodies," Rowett said. "We've had to deal with about 50 long throws in the box, they're really direct from those situations and difficult to play against.
"I thought for the first 25, 30 minutes we made some things happen in the 5-2-3 formation, we looked fairly comfortable. We got into some good positions, worked Camp a couple of times, he made a couple of good saves but not enough.
"It was just that final ball, that final bit of quality. I thought we lacked composure the last 15 minutes of the first half, we just started to get a little bit frantic. Both teams did it, but us in particular, we just tried to force the ball rather than settle and play with composure.
"Second half we started to play with more composure, we started to get down the sides, the likes of Jed and Mahlon started to combine really well.
"We got into some good positions and just couldn't find that final bit of quality. We changed the system twice in the game, we've thrown more forwards on and we tried to do everything we could to win the game.
"Again, sometimes games like this are just decided by one bit of quality. I didn't think we could find it. Camp's made two or three good saves again second half but I'd like us to have worked him a little bit more.
"I don't think we could have done much more. We tried to create chances, sometimes it's just that final bit of composure that defines those top six, top 10 positions in this division."
Image: Millwall FC