Resumed event lockscreen

Hi, in my iPad app i need to do something when the user comes back from the lockscreen, i used the resumed event and it works but with a problem, the resumed event is called also when the user comes back from the multitasking bar or from the springboard, but i don't need to do nothing in this situation.I tried the following code: Ti.App.addEventListener('resumed', function(e) {

if(Ti.App.getIdleTimerDisabled()) {
    alert('Call from Lock');
} else {
    alert('multitask');
}

});

but Ti.App.getIdleTimerDisabled() is always 0 and i can't see alert('Call from Lock'); How can i do?