Display does not turn off

[yongkailoon]

Hi there everyone, maybe some of you would have noticed that I have another thread opened due to heat issues with my Dell XPS M1330. Now I have one more issue with Ubuntu which is that my laptop's display does not turn off even if I set it to turn off after 12 minutes if idle. What could be the problem here? :(

Thank you in advance and sorry if I have too many questions to ask as I'm new to Ubuntu.