The log file of the Neotys Design Studio Controller contains all the errors in the Controller.
It is the file accessible:neoload.log
C:\Users\<user>\AppData\Roaming\Neotys\Neotys Design Studio\v5.5\logs\ (Windows Vista/Seven).C:\Users\<user>\AppData\Roaming\Neotys\Neotys Design Studio\v5.5\logs\ (Windows Vista/Seven).neoload.log