Installed on my Galaxy S4

[homeb]

Installed on my Galaxy S4,
But the light does not change for night time.
What did I miss?

[Tungsten_smooth]

@homeb Need more info, is your device "rooted" meaning you have true full access to basically everything? If not, you will not have access to the warmer colors with f.lux.

If you'd like to root, search the "XDA" forums about it. They are very trustworthy.