Have you set "Auto skin change" in your RoadRunner config ?
The general.ini in the skin folder holds a Daytime= and a Nighttime= value. RR looks up those values. When "Auto skin change" is activated, RR automatically switches to the according skin.
I guess that's your problem. You manually switch to the night skin, rr reads the mentioned values of the night skin and automatically switches back to the day skin.
Turning off "Auto skin change" or deleting those settings in the general.ini of the skins should help.