Overdue Calculation with Conditions

Hello,

I have a "Due Date" column and a "Complete" column.  I want to create an overdue days column.

If 1) the complete column has not been checked, and 2) today's date is past the due date, then I want the overdue days column to calculate the number of days (net days and not work days) past the due date.

I've looked at other threads on here with a similar title, but when I try to modify them to what I want, I keep getting the dreaded #unparseable!  So frustrating.

Any help would be welcome!

Thanks!

George