Populate a ComboBox with strings

[masterej]

I'm trying to populate a ComboBox (dropdown style) with strings of text
from an ArrayList. The ComboBox is actually being populated with the
correct items, however, they appear only as blank entries on the drop
down list. When I click on one of the blank entries, the editable
region displays the correct text, and subsequent functions relying on
this string execute properly. My question is why can't I see any of
the values that have been populated? I know that they are there. Here
is the code I'm using to populate the combobox:

foreach (String s in cats)
{
string formatted = ConvertToUpperCase(s);
comboBoxCat.Items.Add(formatted);
}

Thank you for any assistance.

-MisterE