Start all machine by Connexion button not work

[Issam]

Hello,
I am trying to connect to another PC using the "Connect" button. I enter the correct username and password, but I see in the other PC that it refuses the information entered, and gives the message "Incorrect username or password". I try other users, but I notice that Veyon student activates the user recently opened and not the one I ask, moreover even if I enter the password of the user recently opened, that does not open not and gives the same error message.
Can any one help me !