Lisa,
Very happy to hear your actions are getting approved. It's exciting for us to hear about our user's pretty cool uses of Open Graph stuff, so glad we could help you along the way to learn what you were doing.
Collections are the replacement for 'Aggregations'. They just announced this around when you were submitting, so not surprised you got a taste of both. For more information, see:
developers.facebook.com/blog/post/2013/0...er-part-of-timeline/
We're still investigating them a little, though it doesn't look like there's anything we specifically need to enable for them, outside of the Open Graph Actions we already help implement.
As for why it's not showing after you got your collection... well, I'm honestly not sure. That blog post may help as it discusses an overhaul to the Timeline in general. It's possible the collections don't show in the 'old' Timeline view, in case your profile hasn't been updated yet (they are updated on a rolling basis over a few weeks). Don't know enough about collections yet to have other guesses. If you figure anything out, or it just starts working, please let us know!
Thanks,
Alex