Plunker: http://plnkr.co/edit/Sjfb3Esx1NsjwaYGLMGZ?p=preview
Accordion is in the servers tab.
The plunker actually works. My real app does not. The only thing that plunker is not really replicating is the ui-router stuff. On my actual app the accordion won't open. Other questions on SO say that ui.bootstrap is not included and that fixed their problem. I do have ui.bootstrap included though.
I've also tried copying and pasting the example from http://angular-ui.github.io/bootstrap/ that doesn't work either.
I'm at a loss for what else to look for.
More info:
I'm not getting any errors. Also other ui-bootstrap directives work just fine. I'm using tabs on this same page, and modal and dropdown work on other pages.