The only time I've seen that error pop up in the past, is when whether the 'userconfig' folder, the task_force_radio folder, and/or the .hpp file itself, were misnamed. If everything is in its correct and proper place, and that error still occurs, then it's likely something to do with the pathway from where the game is calling up the mod, and then the mod calling up specific files.
While this may not necessarily be the issue you're facing, it is the only issue I've encountered where it'll do such.