I have two date fields. I want to make sure dateField2 is greater than or equal to dateField1. A null dateField2 is also acceptable. The comparative operators for CompareValidator all make sense to me, I'm just not sure how to also pass validation if dateField2 is null.
The CompareValidator will not validate if one of the values is null. You can try setting the Visible property of the validator to false if dateField2 is null - this way it should not trigger at all: dateField2 != null