Help! just hooked up my Apple TV, when I try to mirror

I just received a Apple TV and I need help to screen mirror from my Iphone to apple to TV. When I select my xfinity stream app on my iphone and then mirror screen it will not work. I receive the following message:

"License Issue, this video stream is not playable under the current device conditions. Please disconnect any external devices (including AirPlay) and try again.

is it possible to mirror my xfiniti from my Iphone?