Error selecting tdm-trinity

I'm pretty sure I had this problem before with an older version of Ubuntu and TDE, but I don't recall how it was fixed. Starting with a fresh install of Ubuntu 15.04, I installed TDE according to the instructions at https://wiki.trinitydesktop.org/UbuntuInstall#For_Vivid_.28Ubuntu_15.04.29 During the install of TDE, it asks me to choose between lightdm and tdm-trinity. I chose tdm-trinity. It gives an error: WARNING: /lib/systemd/system/tdm.service is the selected default display manger but does not exist initctl: Unable to connect to Upstart: Failed to connect to socket /com/ubuntu/upstart: Connection refused insserv: warning: script 'tdm-trinity' missing LSB tags and overrides insserv: Default-Start undefined, assuming empty start runlevel(s) for script 'tdm-trinity' insserv: Default-Stop undefined, assuming empty stop runlevel(s) for script 'tdm-trinity' Rebooting brings me to a command prompt instead of the GUI. If I log in and do startx it brings up some kind of GUI with no icons or panel. The only way to get out of it seems to be to power off the machine. Also tried dpkg-reconfigure lightdm which failed with the same error when I chose tdm-trinity. If I select lightdm things seem to work once I figured out how to tell lightdm to start TDE instead of ubuntu. Thanks in advance.