For some reason I am not able to stagger giants while trying the first version of this shout. I hear the word and see the blue light that appears but nothing happens to my enemy. I tried this on Anise and it works but not on a giant. I should also mention that I havent gone to Hrothgar or Ivarstead yet. Are giants resistant somehow or is there something I need to get from the Greybeards before this will work on everyone?