My Sport Cruiser is equipped with dual HDX’s with both AP & KNOB Panel Modules, Garmin 796 and Garmin GNC 255 Com/Nav. Pilot HDX is set with PFD on left, MAP on right and bottom EMS. Flying with either the Skyview or 796 GPS functions works great, however, I can’t get the Garmin 255 NAV 1 function to activate even though it displays in green in the lower right function box on the PFD. The NAV needle is frozen at 10 degrees regardless of VOR or other frequency setting. Have printed out HDX Pilot's Guide and studied, but this "old dude" would appreciate any help. Was looking to learn from Dynon at Oshkosh, but here that is now cancelled.