According to this NY Times article, the Federal amusement tax wasn't added until 1932:
http://www.nytimes.com/2009/01/07/sp...pagewanted=all
Also Chris Counts had a hand dated 1929 ticket in the BST section to a preseason game between the Phillies and the Athletics. I know it's not a bleacher ticket but it shows Connie Mack's signature and no added tax.