Exit App in Air for IOS

Dear Friends,

iam creating a IOS app. in that I wan to add close button. when user click on the close button, app should close and end. I used the following code.

function close_clicked(event: MouseEvent) {

NativeApplication.nativeApplication.exit();

txt.text = "quiting";

}

It is working in my desktop. when I install in to my Ipad its not exiting the app. Pls help me.

even I added that " <key>UIApplicationExitsOnSuspend</key>" in xml file also.

Thanks and Regards,

Syed Abdul Rahim