apple tv will not connect to my iMac anymore???

Model MC572LL/A which is a second generation according to everything I can find, AND also is among the requirements for the new iOS software release, refuses to work anymore after the update to the newest version of iOS. What happened to all things Apple, simply working together? Used to be, all I had to do was just plug the devices in, upgrade them to the most recent version of software and get the settings all setup, and low in behold they just worked. Can someone please tell me what else I can do besided what I have done already to get my A TV to communicate with my iMac so I can watch videos on my tv screen through Home Share?

Apple Tv has successfully been updated

Apple Tv settings has been set for "Home Share"

iMac 27-inch, Mid 20011 has successfully been updated

iTunes has been successfully updated to newest version

iTunes settings has been setup for "Home Share"

Besides the above, I have taken the steps of multiple sign outs/sign ins

This has been going on since the upgrade to the newest version of iOS and I can't think of anything else to do but come here for help. None of the help documents seem to help, because they seem to indicate ONLY the same types of steps that I have already taken. I would greatly appreciate any help I can get.

Thanks