A broker who is unsuccessful in effecting a transaction in behalf of the principal is not entitled to commissions upon the success of another broker, unless the principal gives him an exclusive agency or promises to pay him a commission even though another agent is successful. Long v. Herr, 10 Colo. 380, 15 P. 802; Goin v. Hess, 102 Iowa, 140, 71 N. W. 218; Letshaw v. Moore, 53 Kan. 234, 36 P. 342; Walton v. N. O., etc., R. Co., 23 La. Ann. 398; Ward v. Fletcher, 124 Mass. 224; Danville v. Comstrock, 110 Mich. 693, 69 N. W. 79; Thuner v. Kanter, 102 Mich. 59, 60 N. W. 299; Emberson v. Deane, 46 How. Pr. 236; Owens v. Wehrle, 14 Pa. Super. Ct. 536; Powell v. Anderson, 15 Daly, 219, 4 N. Y. S. 706; Wilson v. Alexander (Tex. Sup. '92), 18 S. W. 1057; Hennings v. Parsons, 108 Va. 1, 61 S. E. 866. See also Sec. 445.