Calculating a date by using today and parameters

I have defined some parameters in my report, @staDate - type Date/Time, default value an expression =DateAdd("d",0,ToDay), @Consdays - type=Integer, @Demanddays - type=Integer.

In my SQL I use them in a LEFT OUTER JOIN like this; demand.Porddate > DATEADD(dd, + @Demanddays, @staDate)

But it is not working. I wonder if the format of the date to the left is important, because if I instead of DATEADD use a string '2016-01-25' it works. Any idea ?