open the OnSpawn script for the creature.
Make sure that the line that says
SetSpawnInCondition (NW_FLAG_IMMOBILE_AMBIENT_ANIMATIONS); or
SetSpawnInCondition(NW_FLAG_AMBIENT_ANIMATIONS);
is uncommented. meaning that it does not have the // in front of it.
recompile the script. IF you do not want every creature in the game to have the animations you may want to save the file under a differant name before compile it. Just make sure your creature has the new script for there onspawn event.
as long as you are using the default scripts for you NPC's that is all it should take.