comboboxes and dates/times

[nozware]

I am trying to create a series of comboboxes for a timesheet application which relies on dates and times. I am using references to an Excel spreadsheet to get the dates and times, and they come up fine, but whenever a value is selected, the numeric version is displayed in the box, rather than the dd/mm/yy or hh:mm. How can I set it to display the correct format?
Listboxes have no such problems, but I need the facility to enter values that aren't listed.