Facebooks shows only some images

[micropalla]

Hello everybody.

I've got a Coppermine Gallery 1.5 installed on my website.
I've got lots of album and image.
Sometimes I use to post some of them on Facebook simply adding an URL like this in the field of FB:

http://www.fotoferrovie.info/displayimage.php?album=408&pid=2461#top_display_media

Now the problem is that sometimes Facebook creates the thumbnails of the images and sometimes not.
So sometimes there is the image on the left and then the link to the Album on the right of the box and sometimes only the link on the right to the album without the image on the left.

I really don't know why. All albums are the same, no protections, no password, nothing at all...

Any ideas?

THX!

[micropalla]

Tried to fix with meta_tag plugin.
Something bettere but still some problems.
I'll update you tomorrow...

[Αndré]

Are there any official docs how Facebook detects thumbnail images on external websites?