Action link in Union Reports Not Working in OBIEE 11g

Hi- I have a report in Obiee 11g which has two queries in union.

Query 1: Region, Month, Amount
Query 2: Region,'ytd'(Hard coded in edit formula section of the column),Amount---this is done to get total amount for the year

the results from these two queries are pivoted. So my report layout is like below

Region,Jan,Feb,Mar,Apr,May,Jun,July,Aug,Sep,Oct,Nov,Dec,YTD

Region in rows, Month is in Columns and Amount is in measures.
Now, I have an action link for the amount. So when user clink on the amount it takes them to detail report which gives information about all the accounts for region by month. My drill down report is working fine for all the months except for YTD. Since month and region is prompted it is looking for Month='YTD' in drilldown report soo it is not giving me any results. YTD is an hardcoded value in my union report. This values is not present in the table.

Can someone help me with this.

Thanks