I have upgraded my Carlson Civil Suite from 2015 to 2016, both running under Civil3D 2012. The ribbon under 2016 is blank with a note saying that no panels or tabs were loaded. I also installed 2016 on a new computer that did not have a previous installation of Carlson, and had the same thing happen. When I upgraded from 2014 to 2015 I did not have this problem.
I have tried installing every new update issued by Carlson and get the same results. I have tried each of the 'updates' to Carlson 2016 and none of them have implemented the ribbon.
I have managed to do a 'work around' by saving the 2015 arx file to a more or less accessible location, and importing it into the 2016 installation, but I'm pretty sure this isn't the 'right' way to do it.