Unable to locate package Greenbone

Question

Hoping someone can explain to me what the problem is with the below screenshot?

I recently installed Ubuntu 16.04 server on Raspberry PI and I am trying to install Openvas,

Answer 1

It is not in the repository, you can get it at this PPA

sudo add-apt-repository ppa:mrazavi/openvas && sudo apt-get update
sudo apt-get install greenbone-security-assistant 

Here is a list of other packages supplied by this PPA

greenbone-security-assistant9
openvas-cli 
openvas-libraries
openvas-manager
openvas-scanner 
openvas9-cli 
openvas9-libraries 
openvas9-manager 
openvas9-scanner 
rats