Mufasa's feelings

Throughout the movie, Mufasa could sense the weight of the herds of animals, and by extension their species. His feelings were truly extremely strong. So why couldn't he sense Scar's betrayal? Why couldn't he sense Kiros and his pack? You might say there was a snowstorm there, so he couldn't sense it. So how could he not sense Kiros and his pack until they got to Milele?