this may be problem replace this
Intent intent = new Intent();
to
Intent intentAlarm = new Intent(context, SomeTask.class);
it should be like this
public static void cancelAlarm( Context context , int requestID)
{
Log.v("cancelling", requestID+"");
AlarmManager alarmManager = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);
Intent intentAlarm = new Intent(context, SomeTask.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(context,
requestID, intentAlarm, PendingIntent.FLAG_UPDATE_CURRENT);
alarmManager.cancel(pendingIntent);
}