Crystal Reports What is wrong with my formula

Message

     I am trying to create a formula that will look at a parameter DateTime and determine if it is greater than the DateTime in a field.  If it is greater then the result is the parameter time, if not the result is the field time.  This is what I have

timeVar x := (Time({Command.SCAN_CREATE_TM}));
timeVar xx;
IIF (x>Time({?End Time}),xx:=Time({?End Time}),xx:=x)

The result ends up being everything becomes the parameter time.  What is wrong?  Thanks.