HI Ankit,
Did you try the below variable?
JAN= "Sum([Currency Impact USD] Where([Month] InList ("1"))) ForEach([Inflation].[Plant Code];[Analysis Group Code])"
You don't need to use month object in report at all.You have to use only material group, consumption ,JAN,FEB,.... DEC objects in your report.After populating the values, apply alerts.
--Subbu