Home sharing ("Shared Libraries" button) not working?

After turning on home sharing on my old PC & my new Mac, I cannot access the Shared Libraries button. It is selected on the menu bar on the pop up menu. But it doesn't actually appear there unless I hit edit. I've updated both iTunes to the newest version, i have the same account used on both of them. I'm not sure why it isn't working, because I've followed all the instructions.