A real estate broker employed to procure a purchaser of land for a fixed price, or any other price below that consented to by the owner, has the burden of proving that he produced a person with whom the owner reached an agreement of sale or exchange, and that such person was able and willing to carry out such agreement, in order to recover the commissions provided for. Hunt v. Tuttle, 133 Iowa, 647, 110 N. W. 1026; Blackledge v. Davis, 129 Iowa, 591, 105 N. W. 1000; Watters v. Dancey, (S. D. Sup. '09), 122 N. W. 430; Williams v. Phelps, 171 S. W. 1100, - Tex. Civ. App. -; Low Moor Iron Co. v. Jackson, 84 S. E. 100, 117 Va. 76; Joffe v. Lederer, 184 N. Y. Sup. 585.