Is your UST in hiragana? That could be a good explanation for the question marks. There is a plugin you can add to UTAU that converts hiragana to romaji (or vice versa), I don't know if I can post the link as a new user but it's very easy to find!

Hope it helps.
Otherwise, you might have to insert the lyrics manually... A bit tedious, I know, but if you put your lyrics in a text file first so you can divide the syllables (assuming it's japanese) and copy paste the result then when you add it to your Vocaloid project it should be a breeze. Good luck!
EDIT: Just realized this was a thread from months ago, I'm sorry!