BencodingAlarm manager does not play custom sound

I am using Bencoding module to set alarm on android device , it played the default well but when i want to change it it does not work ... here is my code

' var requestCode = 41; var alarmModule = require('bencoding.alarmmanager'); var alarmManager = alarmModule.createAlarmManager();

alarmManager.addAlarmNotification({

requestCode:requestCode,    
year: now.getFullYear(),
month: now.getMonth(),
day: now.getDate(),
hour: hour,
minute: min, //Set the number of minutes until the alarm should go off
contentTitle:'Alarm Wake up', //Set the title of the Notification that will appear
contentText:'Alarm & Notify Scheduled', //Set the body of the notification that will apear
sound: Ti.Filesystem.getResRawDirectory() + 'alarm.mp3',

// playSound:true, //On notification play the default sound ( by default off ) vibrate:true, //On notification vibrate device ( by default off ) showLights: true '