Expression Box Calculation Error

I have displayed the output of a query in a table. One of the columns in

the table shows 'Creation Date'. So I add an 'expression box' to the

table and enter the following expression in the Formatting Custom tab...

NSTR(DSUB(@Creation_Date,NOW(),'D'),'M')

The objective is to display the number of days lapsed since the record

was created on each row of the table. The system keeps returning -14018

or some other garbage on each row.

Please help.