Messymyrna

In an auction today the bidding went 1NT - 2D* - P - 3D P - 3H - P - P P Before the opening lead .... the 2D alert was first asked re meaning. The 3D bidder said they played Brozel meaning D + H. Declarer says nothing. Dummy comes down with 5D and 3H. It turns out that the declarer thought they were playing Capp and the 2D was meant for majors. Brozel is listed on their convention cards. Is declarer required to tell ops before play that he meant the 2D as Capp. 3H makes but could have gone done -1 with better defense and declarer claims "ops should know that his hand isn't D and H looking at dummy's 5D. Director scores it as -1 with the reasoning that IF the declarer had said he forgot convention, he would not have had to disclose but since declarer says he was playing Capp he must tell ops before the beginning of play..... therefore the score is 3H -1.