I think Papito is right, My zuchinnis this year are cranking out fruit faster than I can eat and use them- but I have LOTS of bees busy in my garden and nearby. The ones that dont get pollinated turn yellow and shrievel. You may try and hand pollinating to see it it makes a difference. Get a small paint brush, and pollinate the female
flowers (the one with the baby zuchinni behind it by hand, by brushing off some of the pollen dust from the male
flowers, and brush it in the center of the female
flower. If it takes, you will have a zuchini
growing in no time!