I had SH404SEF installed and for awhile it was using the image I specified there, but then it quit working altogether. I uninstalled SH404SEF, but still can't get it to work. I am able to go to the facebook debugger and scrape. It comes up with a couple errors about og:title being missing, but I don't understand them. I thought JFBConnect took care of that kind of thing.
I just re-scraped your page on the Facebook Open Graph Debugger and the errors shown indicate that Facebook is having a hard time reaching your site.
The most common cause of this that we've seen is that GZip Page Compression is enabled in Joomla global configuration. In some server configurations, this can prevent Facebook from being able to connect. Please see our common support questions at
www.sourcecoast.com/jfbconnect/docs/common-support-questions for "My Share Preview is Incorrect" for tips on how to resolve this. If it ends up not being Gzip compression, there is still something else going on with how your site/server/firewalls are configured that will need to be remedied before Open Graph tags will work correctly.
Anyway, what I would like is to have it use an image in the article when I share, but if there is no image, fall back and use a specific image for when none is in the article.
Is that possible? Also, I'm using K2.
After you resolve the connection errors, this should be easy to do. With a combination of our Open Graph K2 plugin, creating an object in JFBConnect > Open Graph area and setting a default image in the JFBConnect > Open Graph > Configuration > defaults setting, you should be able to set an image and a fallback image. Please see
www.sourcecoast.com/jfbconnect/docs/open-graph/tags-for-joomla for more detailed information on how to set up the objects/defaults.
I think this will help you get past your hurdles, but let me know if you need more clarification.
-Melissa