No Klas : it doesn't work for this message.
I have changed the title of my post because it isn't the no-access message, but an error message.
In Extensions > Langage > Substitutions, I discovered that this message is :
COM_CCK_ERROR_MAX_PARENT_AUTHOR
in the language.ini file. I have substituted it by : "blablabla"
Now, the message still displayed in an error box, like that :
"Erreur
blablabla.
Une erreur est survenue"
How can I custom the full text and the html of this error message please ?