Share to facebook problem

Hello .
I want to share my topics to my facebook page , so Users will come to the forum.
The problem is that when im going to share a specific topic , the image isnt displayed in the facebook!
Im not talking about the forum logo (which i chose to be blank) , Im talking about the photo , in the beggining of each topic.
Help please.

Hi,

Could you be a bit more specific? You're manually sharing it? Or are you using a script for instance? Also, could you provide us with your forum's URL?

Regards.