For future debugging efforts, having
a decent error catcher running will be a huge help. Trying to inherit from a template that doesn't exist will definitely trigger a Lua error.
If you're creating frames in XML, you can check the World of Warcraft > Logs > FrameXML.log file; it will show you all TOC- and XML-related errors, including attempts to inherit from templates that don't exist, attempts to load files that don't exist, etc.