You have entered a calculation, but the functions are not being recognized as shown in the screenshot below where DateTimeNow() and DateAdd() are not being recognized.
When this happens, it is usually associated with a data connection, where the user has kept the data external. This is very easy to do because many users often click OK past the screen shown below, where they should manually change the radio button ...
When the data table is kept external, Spotfire will only be able to apply functions that exist in the source, which in this case was a SQL database. DateTimeNow() and DateAdd() are Spotfire functions. Thus, they do not work if the data is kept external. The solution is to simply import the table.