Rated 4 out of 5 stars
Dhaval, it works fine for me. I think something may be corrupted for you.
Regarding the add-on, it does what it says. But ideally I would like one like the Google Dictionary for Google Chrome (that's really great, pop-up results instead of a new page and - a luxury - spoken word).
Current version gives some errors on console but I contacted the dev and hope he fixes it.
@Firemonkey, mine I have besides the address bar and it sticks there.