Day and Night Cycle help pleas!


Im some what new, but im lurning a lot by reading here and watiching videos.
Im at the moment trying to do a Day and Night Cycle.

It some what works, the light turns from day to night, well the night is only sunset but its dark. and not a night sky, and i cant see the sun moving.

But i get this Errors.

This is the Blue print im using:

And this is what the night look like:

Thanks for any help!