Combo Box Wizard, Option #3

Hi All,

Does anybody know why the combo box wizard sometimes omits the third option which allows me to "find a record on my form based on the record I selected in my combo box".

I get very discouraged when this happens because I'm still not clear about what values it needs to do what the third option does. I have tried various things without success. This omission happens only when I have a subform. Why is that?