Today I realized that my share buttons doesn't work for the new Facebook layout - Timeline. When I was using the Wall everything was working. But now I'm with the Timeline and can't share anything, so I think all the users which are using the Timeline and not the Wall can't share with my buttons at all. The popup appears but the fields are empty and when form is submitted it says something like "The post can't be shared (or saved) to this Wall" (I translated it because my Facebook is not in English). For my buttons I am using sharer.php:
https://www.facebook.com/sharer.php?app_id=<app_id>&sdk=joey&u=<url>&display=popup
Any ideas?
The sharer.php endpoint has been officially deprecated for more than a year. It looks like Facebook might be in the process of disabling it now.
You should switch to either the Send button or the Feed Dialog method.