How do I make a Smart Playlist based on content rating of songs?

I want to make a smart playlist to list all of my songs that are clean, explicit, or neither. It appears I should be able to do so as in this picture, but what do I put for the value to compare to? I've tried "Clean" and "Explicit", as well as "clean" and "explicit", but they get no hits.

I should note that in an exported XML playlist it does have the Clean tag.

Any ideas?

Thanks.