Q:

Get facebook comments from fan page post/update

When I create a new item it is posted to a fan page (http://www.facebook.com/pages/stadsklassen/101802476536649?sk=wall) and I get the postid as reponse which I store in the database next to the new created item.
I would like to display the comments from each individual post from the fan page on the correct page on my website using the postid I stored in the database but it doesn't work.
This is the code I have that should be displaying the comments:
<div id="fb-root"></div><script src="http://connect.facebook.net/en_US/all.js#appId=APP_ID&amp;xfbml=1"></script>
<fb:comments xid="<?php echo FAN_PAGE_POST_ID; ?>" numposts="10" width="600" publish_feed="true">
</fb:comments>

I thought I could do this with the xid but apparently it just creates a new unique id

A:

The FAN_PAGE_POST_ID is NOT the xid, have a look at the comment table. I suggest you query this table with the FAN_PAGE_POST_ID as your post_id to check if you can get the xid.  
P.S: I don't think what you are trying to do is possible as I've never seen it.

