Rather than dragging a new combo box (from the Toolbox toolbar) onto your form and then trying to assign the field to it, drag the field itself from your Field List (on the Form Design toolbar).
The Field List button looks like the attached.
If when you've dragged it to your form it looks like a Text Box, right-click, Change To... > Combo Box.
HTH
Gram
The Field List button looks like the attached.
If when you've dragged it to your form it looks like a Text Box, right-click, Change To... > Combo Box.
HTH
Gram
