Nested IF Statement

Hello,

I am trying to create a status of "Adheres" or "Past Due" based of off comparing two date fields (A Target Date and an Actual Date).  When I use this formula I get what I need.

=IF([Target Audit Start Date]8 > [Actual Audit Start Date]8, "Adheres", "Past Due")

The issue is that the actual date field will not be populated until it happens - so when the Actual Date field is empty the formula returns the value "Adheres" - which is not true yet because it has not happened.

I was thinking I could use a nesting IF Statement that if the Actual Audit Start Date is no value (empty) then put "Pending" but if the date is present then use the formula above.

I tried this IF OR but I keep getting an invalid operation error.

=IF(OR([Actual Audit Start Date]4 = 0, "Pending", IF(OR([Target Audit Start Date]4 > [Actual Audit Start Date]4, "Adheres", "Past Due")))

Any thoughts on how I can accomplish this?

Thank you!