I still does not know why it not worked previously but now its is ok. It was about my enviroment.
Not worked on: host ubuntu 12.04 lts_x64, virtualizing (vbox 4.1) x64 windows 7
actually I made new machine and plugin works properly.
Works on: the same host ubuntu 12.04 lts_x64, virtualizing (vbox 4.3) x64 windows 8.1.
Firefox/chrome for both.