Can not get clock setting

Can not get clock setting to correct time. I have followed the instruction manual and each time I get the clock and date set by the flashing green light in the set-up mode and push enter it reverts back to the time that is on the unit prior to trying to set. It acts as a default time and stays approx. 5 minutes behind the correct time. My remote is very simular to the manual one but not quite the same. The enter is a curved pointer. Unit # is 0710006337. It appears that a default pre-setting of time cycle is not working correctly. Thank- you for your help. braddbauman@cox.net