unity8-lxc-setup where is the installation log?

I installed(?) unity8 in lxc in Vivid:
apt-get install unity8-lxc ... ok ... I find log in /var/log/apt
unity8-lxc-setup ... run ok(?) ... but I'm unable to find log of the installation (/var/log/lxc/unity8-lxc.log is empty)
may you help me? (I have a black screen with arrow logging to unity8 in lxc from LightDM)