If it seems this extension doesnt catch all bookmarks and you dont get the sucess message, then it's usually because one (or more) url is not correct in your bookmarks (no http:// or such). It can happen sometimes, try to find wich one

To the author > this extension is great, but to avoir above problem, you should try to add some try / catch to avoid incorrect url, i added one around line ("var newURI = ioService.newURI(newurl, null, null);") to correct and find the bad url.