In order to stream videos on YouTube you must have a channel created and have live streaming enabled on your channel.
If you are trying to go live on YouTube for the first time please make sure you have channel created on YouTube. For details please see
https://www.youtube.com/create_channel
If you already have a YouTube channel but your scheduled stream fails please make sure you have enabled live streaming on your YouTube channel. To enable Live streaming on your YouTube channel please follow the instructions given here.