Microbit error : service, charasteristic are not published by the connected device

hello, I am trying to create an app for school and I need to send messages ("a", "r", "d", "g" or "s" ) simple messages to control my microbit but when I try to send this message with a button, there is this error, how can I do please?

Hello Amine

You will find the answer in one or more posts on the forum: