Usually, this occurs since the bot has not been attached to the channel you are currently using. Here are things to solve this problem:
Log in as Administrator.
Go to the Bot Settings menu.
Click the Bot Manager page.
Select your Bot.
Click the 'channel deployment' button ( ) on the bottom of the bot.
3Dolphins will redirect you to pop-up channel deployment. To add the channel, select channel and click the 'plus' button ( ) on the 'Available Channels'.
If the attached is successful, you will see the selected channel before on the bot channels section.