Thanks for the response billmeye,
If I take the "Day_1" column out of the query it works. I also tried the "datediff" function and I still get the same error.
I am currently working on a report and I am trying to build a query that keeps giving me this error: "Data type mismatch in criteria expression" In my first query, I am calculating the difference between two dates to get a day until our ship leaves port (ex. 6/12/13 minus 6/10/13 = 2 Days) with...