facebook comments not show

hello,

thanks for an amazing plugin.

i conifg the plugin prefectly,
1. publish post on the site the post pbulish on facebook wall -- > works prefect
2. user comment on the blog post , publish on facebook wall -- > works prefect.
3.user commecnt on the post in the facebook wall , comment wont show on the blog , even after 1-2 hours - --- > not working!
4.entering the plugin setings , and press "on mport comments now (this can take a while)" --> all the comments apper in the post blog.

* plugin comments plus is runnging.

hwo exactly the script of adding comments from face -> wp work ? , is it runing every XX min ?
thanks in advance

amir