What is the test for recovery of a real estate agent’s commission on a completed sale?

Krangle v. Gustavson (1994) 95 B.C.L.R. (2nd) 148 (S.C.) has some similarity to the case at bar. It concerned the collapse of a real estate sale for which the purchaser was found liable. As here, the plaintiffs claimed the real estate agent’s commission on the “second” or completed sale as an item of claimed damages; and also as in the case at bar, it was unclear on the evidence whether the “first” commission had been paid. Mr. Justice Errico observed that if both commissions had been payable by the plaintiffs, “one or the other” would be recoverable as damages flowing from the defendant’s breach. But since the evidence concerning the first fee was lacking, he denied recovery of the second commission, stating that there were “no damages flowing from the breach resulting in an additional real estate commission.” (At para. 5; my emphasis.)