Can't get combobox dropdown menus to appear when tabbing between t
 

I have generated a form that contains several comboboxes. I wanted the
dropdown menu to appear if the combobox is tabbed to. I am using the Enter
Event to cause the combobox dropdown to show. If I tab through the
comboboxes without making any changes, the dropdowns only show up every other
combobox. I want the dropdown to showup on every combobox when it is tabbed
to regardless of whether or not I make a change to the preious combobox.