Do Not Disturb scheduling feature still not working

I have my Do Not Disturb to start at 12am and end at 10am. On January 1st, I noticed that the feature was turned on at 12am but it did not close at 10am. I had to shut it off manually. For January 2nd, it did not turn on automatically nor did it turn off automatically. Again, I had to do it manually.

Anyone having similar issues? I'm using an iPhone 4, iOS 6.0