Doesn't FULLY work with Firefix 8 Rated 4 out of 5 stars

I have used this toolbar for years and have previously edited it to work with each version of Firefox. Unfortunately, it appears that the manual search fundtion is now broken. Whilst I can highlight a word on the page and search for it, if I manually type a word/phrase into googlebar, when I search, it replaces the details with 'null' and searches on that term instead. A previously great add-on unfortunately rendered useless :-(