older cat and kitten problems

why dos my older cant that is almost 6 years old not play with my 4 month old kitten any more she use to play with her when she was first born but when she was 2 months she stoped playing with her and started hitting her growling and hissing when ever she comes by her she is nice to her maby oncea week can u tell me why she is doing this plz is it brcuz my kitten is not spayed yet ? plz help

Thanks

Just making a stab in the dark here but there may be some type of dominance situation going on. Mom-cat is letting the younger one know that she's still Alpha female.

I've seen it happen, heck, it is going on right now where I live...LOL!