Impossible to set CUPS password

English Hardware
1

Hi
I want to install a new Brother DCP 750 CW printer. Following the supplier’s first instruction I entered the following command in order to set a CUP password (as root):
linux-fvze:/home/jaaf # lppasswd -g sys -a root
and get the message hereafter:

Enter password:
Enter password again:
lppasswd: impossible d’ouvrir le fichier des mots de passe: Permission non accordée

What can I do?
Thank you for help.

2

The username and password is your username and password - you don’t have to set one any more.

3

Merci. C’est OK.