Tabbing though form fields

This should be a simple question…

I have a form in Flash. I have the tab order set up thusly:

 
fname.tabIndex = 1;
mi.tabIndex = 2;
lname.tabIndex = 3;
address1.tabIndex = 4;
address2.tabIndex = 5;
city.tabIndex = 6;
state.tabIndex = 7;
zip.tabIndex = 8;

Everything is fine, except the “state” field is actually a combo box component. It will tab from “city” to “state”, but when you hit “Tab”, it does not move the focus to the next field.

Is there some trick to this or some other code or a paramater I’m overlooking? Do I have to make a customer key listener to make it tab off a combo box?

Thanks for your help.