How do I use NativeApplication class to align to user device settings?

My application was rejected by Barnes & Noble for the following reason:

Your application overrides the internal suspension mechanism. Our devises are set to suspend after 2 minutes of inactivity yet had not suspended after 5+ minutes. Please make sure your

application allows user's devises to suspend according to their settings and resubmit.

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I am using the following code. The code in the red in relavant to the question:

NativeApplication.nativeApplication.systemIdleMode = SystemIdleMode.KEEP_AWAKE;

stage.addEventListener(Event.DEACTIVATE, onLeave);

//gets current frame and current scene when the user leaving the app

function onLeave(event:Event):void

{

    stage.addEventListener(Event.ACTIVATE, onComeBack);

    so.data.currentFrame = this.currentFrame;

    so.data.currentSceneName = this.currentScene.name;

    SoundMixer.stopAll();

    stop();

    NativeApplication.nativeApplication.systemIdleMode = SystemIdleMode.NORMAL;

}

//Adds pop-up screen and asks would they like to resume or restart.

function onComeBack(event:Event):void

{

    NativeApplication.nativeApplication.systemIdleMode = SystemIdleMode.KEEP_AWAKE;

    if (!modalW)

    {

        modalW = new ModalW();

        addChild(modalW);

        modalW.x = -97;

        modalW.y = -78;

        modalW.resumego.addEventListener(MouseEvent.CLICK,resumeF);

        modalW.restartgo.addEventListener(MouseEvent.CLICK,restartF);

    }

    else

    {

        addChild(modalW);

    }

}

How do I use the NativeApplication class to allow the user's devices to suspend according to their settings?