I having problem with validation date in my subform.

I have field "txtDate1" "chxEnroll" and "txtDate2" i have wrote validation for the "txtDate2" on form level (txtDate2 > txtDate1). "txtDate2" is only Enable when "chxEnroll" is click. My problem is thata when i input "txtDate1" and then click on "chxEnroll" i can input "txtDate2" and it wil validate the date the way it supposed to but when user clicks on "chxEnroll" by mistake and then then delete the date frm "txtDate2" validation rules still applys to it.

I do want user to delete date if the "chxEnroll" is click by mistake. Any suggestion on how to do this ? Also, i have combo box "cboStatus" if the user clicks on "chxEnroll" then they must pick the status from "cboStatus". what can i do to validate this ?

Thanks in advance