SkyBox Composer uses the native After Effects camera tracker, which usually works well, but is not able to solve everything. In order to track successfully there must be a significant number of items in the shot that do not move. Also - there is a known issue with the camera tracker in After Effects CC 2015 and WIN.
Please try the following:
1. Try to track in CC 2014 - the camera tracker works better.
2. Try to track on Mac OS, if available - the camera tracker works better.
If you are working in WIN in CC 2015, please file a report directly with Adobe.