"Sharing" under "Internet & Wireless" Settings is not available!

I want to be able to share files through my wireless network. Fine, I've done this before. My iMac is set to share. I go to settings on my Macbook Pro, look for the Sharing icon and it looks different like this:

I click on it and I get a blank page with no settings like this:

What happened and how can I fix this? I'm not able to connect to my other computer at all, and am unable to do anything about it and this seems to be the root of the problem.