This article covers possible problems when connecting a resource (group or channel).
Important! Before looking for the error, read the guide: How to connect a resource to puzzlebot.
Common causes:
You are trying to connect the @puzzlebot bot instead of your own bot.
You did not grant the bot full rights (including "Add new admins"). This right is required to add the userbot to the resource.
If you can't connect a channel:
You did not send a post after adding the bot and making it an administrator.