Furigana inserter add on

Can anyone help me with the furigana inserter add-on? It is down-loaded and installed.
On the tool bar it sits beside the rikichin add-on which is working & fab.
When I highlight an area of text, and right click the menu the option to “insert furigana” appears. But there is no action!
This is frustrating; all the reviews say the furigana inserter is a great tool, but there are no instructions how to operate it.
Many thanks,
Gretchen

The add-on page points to this other forum for support. I suggest you ask over there.