Petto can’t assign/remove a role
Petto’s own role must sit above the role it’s trying to manage in your server’s role list, and it needs the Manage Roles permission. Drag Petto’s role up in Server Settings → Roles if it’s below the role you’re trying to use.
In Discord: Petto's role is under Moderators, so it cannot give it.

In Discord: without Manage Roles, Petto says so.
Petto can’t ban/kick/mute a member
Same rule as roles: Petto’s role must be positioned above the target member’s highest role. This also means Petto can never act on someone with a role above its own, including other admins, by design.
In Discord: Petto says which permission it is missing.

In Discord: the member has a role above Petto's.
Commands aren’t responding
Check the prefix
!help (or whatever your current prefix is, see Prefix if you’re not sure). A message starting with the wrong prefix is just ignored, no error shown.
In Discord: a message with the wrong prefix gets no answer; a mention of Petto shows the prefix.
Check Petto is actually online
Check it can read the channel
A slash command is missing from the / menu
The member doesn't have the permission
The member doesn't have the permission
/ban needs Ban Members, /purge Manage Messages, /channel Manage Channels, and /embed or /giveaway Manage Server. Give the permission, or allow the command for their role in Server Settings → Integrations → Petto. See Command permissions.The command only exists with the prefix
The command only exists with the prefix
!automod, !logs or !honeypot are prefix only. See the list of slash commands.It was just added
It was just added
A channel-specific feature isn’t working
Petto also needs View Channel and Send Messages (plus Embed Links for anything using an embed) in that specific channel, a server-wide permission doesn’t override a channel-level denial.
In Discord: Petto's role has Manage Messages, but a channel override takes it away in #general.