Newsmax is on 1115, but our channels go from 1114 to 1121.
use the xfinity my account app, select 'TV' then the link to see your channel lineup. scroll through your subscribed channels. does 1115 show up?
Apparently, not every city with Xfinity has access to Newsmax. It is not available where I live (somewhere between San Francisco and Sacramento), and I have the HBO & Showtime tier. Your guess is as good as mine as to why some cities would have access to it while others don't.