Ubuntu install fails: docker repos not get installed - where is the problem?

General
1

docker repos not get installed - where is the problem?

followed all from
docs.docker.com/engine/installation/linux/ubuntulinux/
Ubuntu 16.04 in Virtual box
removed links below

leonidas@leonidas-VirtualBox:~$ echo "deb https://apt.dockerproject.org/repo ubuntu-xenial main" | sudo tee /etc/apt/sources.list.d/docker.list
deb apt.dockerproject.org/repo ubuntu-xenial main
leonidas@leonidas-VirtualBox:~$ apt-cache policy docker-engine
docker-engine:
      Installed: (none)
      Candidate: 1.12.5-0~ubuntu-xenial
      Version table:
         1.12.5-0~ubuntu-xenial 500
            500 https://apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.12.4-0~ubuntu-xenial 500
            500 apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.12.3-0~xenial 500
            500 apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.12.2-0~xenial 500
            500 apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.12.1-0~xenial 500
            500 apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.12.0-0~xenial 500
            500 apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.11.2-0~xenial 500
            500 apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.11.1-0~xenial 500
            500 apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
         1.11.0-0~xenial 500
            500 https://apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages
    leonidas@leonidas-VirtualBox:~$
2

well can you reply asap??