How do I edit a PowerPoint slide?

I'm having difficulty editing one of my slides (originally from PowerPoint).  I've tried editing in PowerPoint and the changes do not appear to transition back to Captivate.  It might be worth noting that I'm on a MAC.  I've tried Syncing and for some reason it picks up an entirely different presentation when I sync.  Can anyone provide me with some step-by-step guidance?  I would be so appreciative!

Amanda