I have an apple smart cover and it works great. I love that I can put my iPad to sleep just by closing the cover. What will they think of next.
They moved the sensor on the new iPad. Many users of non-Apple covers are having the same problem.
The switch in the new iPad that allows a cover to put it into sleep mode is only activated by the negative (or south) polarity of a magnet. If the magnet in the smart cover you have has the positive (or north) polarity facing the screen it will not turn the screen off. (I have tested this on over smart 20 covers using a magnetic polarity tester). This is a new twist that Apple put in the new iPad. Either polarity will put the iPad 2 into sleep mode, so a case for that device has a 50-50 chance of working properly on the new iPad.