Hi There I Hope Some One Can Help

I Have 3 Parametre Fields On My Report And Depending On What Parameter The Client Uses I Want The Discription Formula To Change

This Is What I Came Up With But It Does Not Work

Discription Formula

IF {?Mobile Number} THEN "An Itemisted Bill For Mobile {?Mobile Number}" ELSE
IF {?Cost Centre} THEN "Itemised Mobile Bill For Cost Centre {?Cost Centre}" ELSE
IF {?Place Called} THEN "An Itemised Bill Based On {?Place Called} Calls" ELSE ""

All Of The Parametre Fields Are String

Does Any One Have Any Ideas To Get This Formula To Work If You Need Any More Information Please Let Me Know