Disappointment Rated 1 out of 5 stars

I have Win X (all updates) and FF 4.0.
After installing ClearFields V 4.0.2 nothing happens! (no buttons, no entry in "tools"-Menu)
Version 3.0.2. still works for me correctly under FF 4.0 (all buttons, entry in "tools"-Menu)
What is the reason?!?
V 4.0.2. is correct installed if I look into the add-on-manager...

This review is for a previous version of the add-on (