The release date for the new album from U.D.O., the German metal act featuring former Accept frontman Udo Dirkschneider, has once again been been pushed back, this time until May 20th,2011, according to reports.  The band has reportedly written 17 songs for the "Rev-Raptor" project, 11 of which have been designated for the finished product.  The reason for the latest delay is back problems suffered by guitarist Stefan Kaufmann, the same back problems that made him quit playing drums for Accept way back.