Dan, Hello again. I am not too familiar with working with Oracle but I can ask some Questions.
When you had the Combo for Order # did it display them OK?
Was the Combo Bound to the Orders_Table Order # Field?
Did it put the Order # in that Field?
Did you try VBA to in the Combo's After Update event procedure to put the Order # in tot an Unbound text box, to see if the order # is actually being "Selected"?
You are doing this on a Form, based on your Access Orders Table or Appointments Table?