Solving the mystery of the black sky

Somehow I've managed to create an abominable mess in my route, relating to the sky. In the last few days, I've tinkered a bit with the time of day files to optimise the sunrise and sunset phases with times appropriate for this part of the world. Somehow, i managed to not back up the route properties xml file in the content folder, and an inadvertent change in this file saw TS2013 failing to start. Not knowing what to fix, I saved the .bin file containing my changes to the time of day, as well as the content folder files and set up a new route with fresh blueprints.
For some reason, exporting the time of day blueprint used to cause a black screen in my route, and I could only make changes by editing the (name of TOD blueprint).bin file in the assets/time of day folder. Now exporting the blueprint seems to work, but there is a black sky where blue is supposed to be in the route. Checking all references to the blueprint, and exporting GreatNortherner's sky textures and skydome models from the source folder seems to do nothing to fix it. Instead, I get a flickering sky which looks as though the game is trying to load two skies, or sky domes at once. Railworks obviously detects the blueprint file, or there would not be the flickering in the sky. So an incorrect path might be something that I can rule out. I've also ruled out graphics card issues, as all other routes have a normal textured sky
Exporting the blueprint without the textures referenced still results in a black sky. In an attempt to fix it, I resorted to a back up .bin file and copied the text into the current file in the time of day folder. This used to resolve any problems that I inadvertently created. However, I still get a black sky after copying this 'clean' block of text. I have a feeling that RW depends on several files to tell it what time of day files it needs to use, but I seem to have exhausted all avenues in getting to bottom of this problem.
There seems to be some gaps in the information in regards to creating TOD blueprints. Do they actually have to have textures listed where it asks for them (Such as dome mesh, dome tex etc)? Or is it safe to leave this blank? Does RW refer to a default skydome/texture set if one does this?
For some reason, exporting the time of day blueprint used to cause a black screen in my route, and I could only make changes by editing the (name of TOD blueprint).bin file in the assets/time of day folder. Now exporting the blueprint seems to work, but there is a black sky where blue is supposed to be in the route. Checking all references to the blueprint, and exporting GreatNortherner's sky textures and skydome models from the source folder seems to do nothing to fix it. Instead, I get a flickering sky which looks as though the game is trying to load two skies, or sky domes at once. Railworks obviously detects the blueprint file, or there would not be the flickering in the sky. So an incorrect path might be something that I can rule out. I've also ruled out graphics card issues, as all other routes have a normal textured sky
Exporting the blueprint without the textures referenced still results in a black sky. In an attempt to fix it, I resorted to a back up .bin file and copied the text into the current file in the time of day folder. This used to resolve any problems that I inadvertently created. However, I still get a black sky after copying this 'clean' block of text. I have a feeling that RW depends on several files to tell it what time of day files it needs to use, but I seem to have exhausted all avenues in getting to bottom of this problem.
There seems to be some gaps in the information in regards to creating TOD blueprints. Do they actually have to have textures listed where it asks for them (Such as dome mesh, dome tex etc)? Or is it safe to leave this blank? Does RW refer to a default skydome/texture set if one does this?