Install failure

Hi there

I’m trying to install yunohost on a Debian 8 VPS server.

After running the install script it screens :

Setting up deb package sources failed

Tried what said on the previous topic about this subject : didn’t work.

Can you please tell me what can I do ?

(You can use English and French for answers)

Solution seems to be here :

apt-get install aptitude
aptitude update
aptitude install systemd systemd-sysv