"I do not have my hats."
Translation:Non ho i miei cappelli.
If you got the select all correct translations list with the following answers;
- Io no ho i miei cappelli.
- Non ho i miei cappelli.
Then the answer to your question is "Io is correct. It is the rest of the sentence that is wrong. It should be "Io non ho" but it says "Io no ho", which is why it fails on that sentence."
I got this one wrong myself and only saw the problem after a bit of a look myself.
Duo's a tricky bastard.