I bought a Keith McMillen Batt-o-meter. When I plug it into my Ibanez SR505 I get a Plug Error ('PL6'). Got the same error on one of my stomp boxes. Assumed the decvice was faulty and sent it back to and received a replacement. I get the same error. Is my Ibanez SR505 (to quote the users manual) "one of the few devices that won't work with the batt-o-meter?" Other suggestions.