combo box update

[vz1]

I have a combo box and the style is set to 2-Dropdown list. I am getting the list from a table in my access 97 db. when i go to add a record and i pick an item from the drop down and then click my update button it works fine but if i try to edit that combo box it will not let me. i have tried to enable my update button but it won't enable for me to save it. Is there a way that i can save a change to this combo box field?? I am using an unbound ado connection.
thanks in advance

[Hack]

Change the combo box style to 0 on its property page.

[vz1]

yes but if i change the property to 0 then they have the ability to save something outside the table and i do not want to let them do that. Is there another way? Also the only way i can get it to change is if they type something in instead of choosing it from the dropdown box, when they choose from the drop down box the update button still does not become enabled. Please help. Is there anyway to edit a dropdown box?
Thanks