Original scene won't render after creating a new one.

I opened a previously saved Blender file, renamed the original “scene” to “scene 1”, reopened the blend file described below and appended “scene 1”. Now “scene 1” with the bullet and broken glass renders as well as the smoke “scene”. I still have no idea why the original “scene” wouldn’t render after creating the smoke “scene”.

I’m following a tutorial here: https://youtu.be/9L8qOq1Shiw Because the smoke won’t render with GPU, he shows how to make another scene (using CPU) copying the camera, lights, smoke domain and emitter to the new scene. I was able to render the smoke in the new scene. But when I returned to the original scene I was unable to render the broken glass. Only the bullet rendered. He shows how to composite the two scenes. But I need to get this fixed first. Can someone tell me what I did wrong?


Blend file: http://www.pasteall.org/blend/37765