Can't reengage Autopilot default King Air 350

Hi all,

Everything goes well when flying on autopilot with the KA 350i and suddenly the AP goes mad, steep descending, climbing. So, stay cool and get it back to normal to switch off AP and stabilize the aircraft. When stabilizing the aircraft (let say 2500 FT and speed within normal range), I can’t reengage the AP anymore. On display AP stays red and nothing helps.

Anyone seen the same issue? Or is it just a captain error :slight_smile: