Cat fights-need help

I have a 14 year old, very active female cat who previously lived with
other animals but has been an only cat for about 7 years. Three
months ago we adopted a female kitten who was 6 weeks old. We gave
them separate areas of the house and did everything we were supposed
to do so they could slowly get used to each other. The kitten is now
over 4 months old and the adult cat hates her. It's more of the kitten
taunting the adult cat, wanting to play. The adult cat understandably
finds this annoying and SCREAMS and hisses at the kitten. It is
LOUD. Both cats are played with a lot and have constant access to
toys, and they both have their own spots for sleeping (not a
competition/territory thing). Neither have any claws, so this is a
matter of constant cat fights/noise. It's incredibly frustrating. We
have tried giving them treats next to each other so they can associate
each other with something positive, and that goes fine, until the
treat is gone, then back to screaming. They use each other's litter
boxes and share food. I really just want my cats to stop the
screaming. Any ideas?