Empty values in Pivot table?

[LostInDaJungle]

I have a series of accounts and period balances coming from a database.

Each line is basically:
Year - Month - Account - Netchange

I'm using Pivot tables to summarize this information for YTD calcs.

I put "NETCHANGE" into the values of the PivotTable and set the name to YTD and the Set the type to running total by month.

I can then call an individual account like so:

=GETPIVOTDATA("YTD",ptAll,"FISCALYEAR",2011,"FISCALPERIOD",12,"ACCOUNTNO","10000000")

It works like a dream except for those odd accounts that don't get much activity. Some accounts did not have a change in December of the target year, so there is no PivotTable line for 12/2011.

I've played with all of the PivotTable options that would seem to "fill in blanks" and none work for me. How can I get my PivotTable to treat empty months as a 0 netchange and give me a total for December?

Here's what my pivot table looks like:

Thanks in advance for your help.