Mousetrap: If you are clicking on the "Add New Item" that is above the smiley setting section, that is the wrong one. That is for adding items to that "context menu" thing.

Adding smileys works fine for me right now.

When I click on the smiley I want to add, you do NOT see it above there where it shows the ones you've already picked in the past. (Or maybe you do if you only have a couple. I'm not sure)
I choose whatever smiley I want to add, and then I click Save and Finish, below that.

Then when I'm in a message and I click that smiley icon, I do definitely see the new smiley added to my list.

Since you say nothing happens at all, the only thing I could think of is that you clicked "Add New Item" above it. I did that earlier by mistake when I was testing it out. Then I noticed that it added a new line above saying "New link".

I just know that it seems to be fine for me, and I'm no one special. LOL