Lastpass 2.0.0 or 2.0.20 does not work on FF19 Rated 4 out of 5 stars

Can find lastpass has been enabled on Add-ons Manager, but the icon of lastpass on toobar will be disappered, it is not working at all. The operating system is Windows 8 64bit. FF18 has no this issue.

This review is for a previous version of the add-on (2.0.0).  This user has a previous review of this add-on.