This could be an indication that the lock’s ribbon cable is plugged into the keypad backwards, that there is damage to the lock’s cable or there could be a problem with the keypad.
Unplug the locks ribbon cable from the keypad and plug it back in. Please ensure it goes into the connector the proper way. Take note of the tabs at the sides of the connecter. 
Inspect the ribbon cable. If there are any hard bends or crimping, please straighten them out. Please contact you safe company/lock smith/distributor for warranty if needed.
NOTE: If the grey flat ribbon cable has been damaged by cutting or disconnected from the connector, the lock body will have to be replaced for the 6120, 6123-6128 models. If the cable is round in a white sheath, a locksmith may be able to splice a temporary connection and you can replace the cable for the Spartan and Titan models.