A plea to a declaration by real estate brokers for commissions averring that the brokers did not sell the property to the purchasers named for the owners for the amounts named, and that the purchasers did not pay the owners such amount for the property, and that the owners never were indebted as averred, was not bad as amounting only to the general issue, as a plea is not objectionable on that ground, unless it sets up matters of fact merely amounting to a denial of such allegations in the declaration as on general issue would have to be proved to support the case. Seff v. Brotman, 70 A. 106, 108 Md. 278; Bradley v. Blandin, 104 A. 11, - Vt. Sup. - .