Sunderland boss Steve Bruce was upset after their Carling Cup defeat to Brighton.
Craig Mackail-Smith's header five minutes into extra time landed the latest blow on Bruce's new-look Premier League team.
He said: "We created enough chances to win the cup-tie but we failed to do that because of our inability, once more, to put away chances
"We've got punished for it and it's worrying. We certainly had enough strikers on the pitch but we just didn't convert our chances . We've got to learn to do that."
Bruce refused to blame defeat on the fact his side are still gelling together after a host of summer signings and six notable departures including Danny Welbeck and Jordan Henderson.
He said: "Over the next few weeks these new signings are going to find out what its like playing for this club and in front of our fans.
"We lost four loan players in the summer as well as Jordan and (Bolo) Zenden but the fact remains that we came back after losing a derby game and went out there with the right spirit.
"All that is no good, though, if you can't take the chances you create. Its a big concern. But you've got to give Brighton credit. They have some very good players and you can see why they've started the season so well."
