What is the Formula for:
IF Submit Date is older than Start Date, Display X
IF Submit Date is newer than Start Date, Display Y
IF either Date is blank, Display XY

Currently I am using a formula that is not giving me the results that I need:
=IF(AO18<AU18,"X","Y")

Part of my problem is that I don't think about the problem in the way that I need to write a formula.
The other part is that I am weak with formulas.

Thanks