No Dateline Channel on Xfinity Stream

I just got a Firestick for a spare bedroom and I'm using the Xfinity Stream app to watch live TV. I was dismayed that I could not find the Dateline Channel (4015) on Xfinity Stream, even though I do have that channel on other TVs in the house that are directly connected to Xfinity through a cable box. Why do I not have the Dateline Channel on Xfinity Stream?