Each month I make an entry to my underbillling account and to my overbilling account and the net goes to my "Overbilling/Underbilling" Revenue account.

The next month the entry for the prior month is reversed and the new entry is posted.  Shouldn't the ending balances of these 3 accounts match the amounts I posted into the G/L? They all do except for the "Over/Under" Revenue account.  It doesn't show the net balance I put in. Am I missing something here?