Affirmed. § 673.403(2)(b), Fla.Stat. (1983); Chiles v. Mann & Mann, Inc., 240 Ark. 527, 400 S.W.2d 667 (1966) (defense that person signing check did so in his representative capacity and was not to be personally liable must be affirmatively pleaded and proved); Colonial Baking Co. of Des Moines v. Dowie, 330 N.W.2d 279 (Iowa 1983) (same).