Issue with IsNull Function in Webi Cross Tab Report which is migrated from XI R3 to XI 4.1 SP2

Hi,

We have recently migrated from XI R3 to XI 4.1 SP2.

In one of our cross tab report, we have used a fomula If( IsNull(<Object>);"  ";"X") which means if that Object is NULL, it will display Null else will display X in the report body.

In 3.1 Report:

In 4.1 Report

It is behaving correctly in XI R3 report where as in the migrated 4.1 report all the values are displaying as "X" though it contains null values.

Is there anyone who faced similar type of issue and got resolved? please let me know.

Thanks,

Prasad.