this error sounds to me like you didn't change the themename or left it blank. the thm file is used for finding the step.rc in your themefolder. if the themename and foldername aren't the same, he couldn't find it. the best and easiest way is, to name the theme as the themefolder, or change it in LSTS, mark your theme and edit the theme settings. they will be saved in the THM file.