hello, i downloaded multi pos module from app storre, i copied the unzipped file in /var/lib/odoo/.local/share/Odoo/addons/, i've stopped an restarted  odoo server, cleared the mozilla cache, refreashed the app list as a developer mode, but nothing, the app doesn't show up 

any  suggestion??

 i installed odoo 11 with this commands:

$ sudo apt install gnupg
$ wget -O - https://nightly.odoo.com/odoo.key | sudo apt-key add -
$ sudo sh -c "echo 'deb http://nightly.odoo.com/11.0/nightly/deb/ ./' >> /etc/apt/sources.list.d/odoo.list"
$ sudo apt-get update
$ sudo apt-get install odoo

please