Facebook Connect Widget won't display

I recently installed Ultimate Facebook, and most features are working well (likes, send buttons, etc.). BUT my Facebook Connect widget is not showing up at all when I add it to my sidebar (or any other widget area).

I tried switching to the twenty-twelve theme to make sure it wasn't a theme specific problem... It would not display for that theme either. My wordpress login page does not have the Facbook button either.

Any ideas?

Background:
I had originally used another Facebook widget/plugin (WP-Facebook-Autoconnect), which worked well, but was not full-featured like Ultimate Facebook. I have since disabled that plugin and removed it.

I have tried:
- uninstalling and re-installed the Ultimate Faebook Plugin (and deactivate and re-activated)
- activating a different theme