Where, in an action for a broker's commissions, there was evidence that plaintiff's agency had been revoked before defendant began negotiations with the purchaser, while plaintiff's evidence indicated that such revocation was made with knowledge that it was through plaintiff's efforts the purchase was made, an instruction ignoring the question whether plaintiff's alleged efforts to sell the land had not been abandoned or his agency revoked before defendant and the purchaser met, was erroneous. Christian v. McDonnell, 127 Mo. App. 630, 106 S. W. 1104.