Oh, so you want to be able shoutout Twitch channels from your Discord server?.. That would have been useful to specify it in advance, haha!
So, having a few Discord bots in development, I don’t think it’s possible to do it with Nightbot, as when you mention someone, you see @USERNAME, but in the client it’s @USERNAME_ID, which is very different.
When you call the command from Discord you feed Nightbot a bunch of numbers to look at as a channel, so of course it won’t find it and return the Unknown Twitch Channel error.
Moreover, it’s not uncommon to have people with different usernames on Twitch and Discord, so this wouldn’t work in these cases either.
For it to work all the time you’d have to fetch the Twitch account they linked to their Discord, and I don’t think Nightbot can do that.
But I can be wrong, I’m not familiar enough with Nightbot’s Discord integration, @night will be able to inform you once he checks the forum and confirm/dismiss what I said.