Hi Phani,
No need for customer exit, you can achieve this in query designer by using REPLACEMENT PATH..
For example, your variable date in PO is PO_DATE..
Then in the date for POVALUE, create a replacement path variable..
In PROCESSING BY select replacement path..
Ref.Characteristic, select the infoobject of date in PO..
Then in replacement path tab, select VARIABLE in replace variable with..
In variable, enter PO_DATE..
In the use interval, choose the TO VALUE..
Let's say you name your variable with POVALUE_DATE..
Then filter the infoobject date of your POVALUE with VALUE RANGE, BETWEEN, get the APRIL 2011 and POVALUE_DATE..
Just post here if you have any question..
Loed