Thanks again. I saw your form.
What I wanted is to display the message when I check either Field 1, 2 or 3.
I have not tried to combine different rules into one group but, on your form, when I tried 3 conditions under one rule, it only displayed the message appropriately when I check field 1 or field 3 OR both of them. However, it did not work when I checked the Field 2 box, .