Missing Train In Game?

I have placed a train on some rails to create the edge of my map, but when i run the map both my train engine and its rails dissapear, both its carriages are still visible however the one closest to the engine is a little glitchy and can partially dissapear also. I have tried moving the train and its rails but that doesnt help.

Specifics:
The train is the northern express and the rails are the train size rails.
Both are taken for ABS amazing prop library

Any ideas?

originally i had the rails going trough the sky box, but then i moved the rails and engine and it worked fine, so i moved it back and made it so it didnt go through the skybox, but still the same thing, now iv removed one of the carriages and moved the engine back, but the engine is now glitchy and the rails were the engine was sill dont show up.

i think i have solved it, i went back and completely re created everything to do with my train, the rails and the carriages and the engine, seems to be working okay now, thanks for the help though, i think i may have just changed a setting accidently.