Where a broker, with authority to sell land at $60,000, secured an offer by C. of $42,000, and a reduction by the owner to $48,000, but could not effect a sale, and the owner's son, with knowledge, sold to C. for $43,500, the broker was not entitled to commissions, the owner being without knowledge. Terry v. Bart-lett, 140 N. W. 1133, 153 Wis. 208.