Elef,
There's a few odd things happening, and I'm not sure what's causing them. I don't think JFBConnect is the issue at all though, but will try to help diagnose as best as we can.
Testing with
www.eleftheriaonline.gr/politismos/synen...575-nick-cave-ellada , if I try to create a Like button for your page using the
Like Button Creation Tool
from Facebook, it doesn't show up there either. If you put any other URL in, like
www.sourcecoast.com, it does show the Like button. So Facebook seems to dislike that page for some reason.
If I run your you page through the
Facebook Debug Tool
, it's reporting a warning that some of your images are too small. JFBConnect is inserting the XL size image for your article, which is correct. K2 itself is adding the S (small) size image, which doesn't meet Facebook requirements. You'll need to contact K2 to determine how to fix, or remove, that Open Graph setting.
Hopefully, just fixing that warning will work. I'm not sure why the Like button won't show otherwise. It's definitely on Facebook's end though since the Like creation tool doesn't work either (which has nothing to do with JFBConnect).
Finally, in your blog view, I can't see the Like button either in addition to the missing Google+ and Twitter buttons. The Like button is missing, I think, for the same reasons as above. The G+1 and Twitter buttons are likely disabled in the Social configuration settings of JFBConnect. Check the view options for the Blog View and make sure that the G+1 and Twitter buttons are enabled.
Hope that helps,
Alex