|I live in Southern California and I planted|
|You may not be doing anything wrong. If the flowers of your squash are not pollinated, the little fruits will be aborted when they are quite immature. You can encourage pollinating insects to visit your garden by reducing the amounts of pesticides you use, and by providing lots of colorful flowers throughout your garden. You can also try pollinating the female flowers yourself by removing a male flower and brushing the insides of a female flowers. (Male flowers grow on a straight stem; female flowers have a small swelling just below the petals.)
Best wishes with your buttercup squash!