Set solartime in SkySUn actor

I have set up a level with a SkySun and want to rotate the Sun(environment) with 2 arrow actors. I have setup the solartime, but when playing on hover it takes a long time to start rotating and then suddenly it goes very fast (within seconds) and stops.

I guess I setup sth wrong, but can’t figure out how to hook it up properly.

Thanks inadvance!