How do I fix the clock in my Blaupunkt 3s4t-18c869-af radio?

My blaupunkt 3s4t-18c869-af auto radios clock resets to 12:00am everytime I turn off the car. When I restart the car and radio it takes 5 minutes and the radio syncs on its own and the time changes to 1 hour later than the actual time. I checked the battery leads, both constant and accessory, they are correct. Any ideas?