Documentation:
href - the URL to like. The XFBML version defaults to the current
page. Note: After July 2013 migration, href should be an absolute URL
Can you confirm that href is an absolute URL?
If yes, try to include OpenGraph metas
on your targeted pages (page specified in href
) like:
<meta property="og:image" content="http://website.com/image.jpg" />
Do not forget to check the size of your image, you can find more details in this discussion
Edit:
Copy your link on the Facebook Object Debugger page and check what Facebook says about your image, that would help to get more details.
Update:
About your question:
Can I use different metas with different pictures? I want ten
different pictures on my page that you can share.
Look at this paragraph in the documentation, you can specify many images and your first image tag will be given the preference during conflicts. Keep in mind that when you share something on Facebook only one image will be displayed.
You may also be interested by setting other OpenGraph metas
so if someone share your page (copy/paste your URL in Facebook) a nice summary of your page will be displayed (title, description, image...).