Try using the Wizard. The "Combo Box Wizard" will take
you through all of the necessary steps to create the Combo
Box.
To display the Wizard, open a Form in "Design View", on
the Menu Bar, click "View/Toolbar". There is a button on
the displayed Toolbar that looks like a magic Wand, ensure
this button is "De-pressed" to run the Wizard. Hover the
Mouse over the displayed Toolbar Commands, you are looking
out for "Combo Box".
HTH.
Tony C.