A broker employed by a guardian of an incompetent person to sell real estate is not entitled to commissions if he offered money to another bidder to induce him to refrain from bidding on the same against the purchaser procured by the broker, and without the guardian's knowledge represented the purchaser, and worked to secure the real estate for him at the lowest possible price. Trees v. Millikin (Ind. App. '08), 85 N. E. 123. See also Sec. 217.