Why my alarm stopped working.

Alarm.rb

class Alarm
  def initialize(alarm_time,music = "/mount/data2/Songs/11.Mazhathullikal.mp3")
    @alarm_time = alarm_time
    @music = music
    @run = true
  end

  def its_time
    system("vlc #{@music} --volume 512")
  end

  def check_time
    while @run
      if Time.now >= @alarm_time
        its_time
        @run = false
      end
      sleep(@alarm_time-Time.now)
    end
  end
end

@alarm = Alarm.new Time.new 2013,03,15,6
@alarm.check_time