Validation List: Wide As Widest List Item

I am trying to make some of my data validation dropdown list boxes narrower. I was told one way to do that is to use combo boxes. (If there are any other ways, please let me know!)

I don't think my combo boxes are working. I had tried to make a combo box appear in each data validation pulldown cell by using this tutorial:

http://www.contextures.com/xlDataVal10.html

I followed this tutorial word for word, but when I try to test the code at the end by double-clicking on a data validation pulldown cell, no combo box appears.