Mature lhasa apso's agression towards new puppy

I have a beautiful 7 year old lhasa, Karma. Two weeks ago I got a new lhasa puppy, Gizmo, now 11 weeks old. Unfortunately, Karma really hates him, growls and snaps at him and will not allow Gizmo to come near him. The puppy has a lovely nature, friendly and playful, and clearly I don't want him to be influenced by this aggressive behaviour. Meanwhile, Karma is very depressed, not seeming to be interested in anything. Help!