Predator wont reinstall after ecm replacement

[turningwrenches]

Predator-U7180X 2004 GMC 2500HD 4x4 6.6 (1) Put programmer back to stock- replaced ecm due to a/c relay control malfunction- tried to reinstall programmer- now says vehicle not licensed to this product- What do i do now? This is a customers truck and i know it was programmed before and i even uninstalled it myself! Any help would be greatly appreciated.....