Node red issue when inject message, the MQTT publish node disconnect

i have a issue when i'm trying inject the node, the MQTT publish node( the broker that i'm using: []) will always become disconnected and the data is not been updated into the my adafruit feeds . I also tried it using node red fred sensetecnic but its still give me a same problem .So, can i know why this thing happen and do you have any solution for that?. Thank you.

If it gets disconnected when you try to publish, that suggests you are trying to publish to a topic you are not allowed to use.

The valid topic structures are documented here:

i already change the topic but it still give me the same problem. Is it this issue occur because of the broker server that i'm currently using?.

Are you using a free or paid account at adafruit?
Have you ever been successful at send/receiving a message?
what does your topic lookalike (xxx out your username)

What platform are you running NR on?
If it is a Pi, have you thought about installing MQTT on it?