Excel drop-down menu

I have a spreadsheet which has 2 columns containing drop-down lists.  After data validation, one column works perfectly -- the item chosen from the drop-down list populates the cell.  The other column shows the drop-down list but does not copy the chosen item into the cell.  

Both lists are in columns in an Excel worksheet.  The list which is not working contains 28 items.

Any ideas for me?

-- Kathy