disabling and enabling screen time-out

Disabling the screen time-out works, but enabling it again after disabling it doesn't work.

Disable:

Code:

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NativeApplication.nativeApplication.systemIdleMode = SystemIdleMode.KEEP_AWAKE;

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Enable (doesn't work after disabling):

Code:

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NativeApplication.nativeApplication.systemIdleMode = SystemIdleMode.NORMAL;

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Anybody have this same problem or a solution?

Thanks!