You need to clear 5 letter words and get the "3" and clear that. Don't work on the 6 letter words that clear whole row.
same thing happens for me. I use the '3' letter tile, but I don't get credit for it if there is a ribbon in the word. Plus it is impossible to get 6 '3'letter tiles used when you only get 12 tries unless you make a five letter word every time you try to get a 3 letter tile to use. I am really stuck on level 105. Please send me a message to my facebook to shelley Johnson McKenzie if you have the answer to how to beat level 105. thanks