got an error compling my query in query designer for my SSRS report.

Got an error , Incorrect syntax near '@PFromDate' . what wrong with this error.

i already declare this parameter to dataset properties/parameter.

even i setting up a SET keyword still have this error (Must declare scalar variable..@PFfromDate)

how could fixed this problem? yourhelp is very much appreciated. thanks.

IF @rowcount=0

BEGIN

@PFromDate=@PFromDate-1

@PToDate=@PToDate-1

END