One male flower can pollinate more than one female flower. It may be that you only had one female flower or that the male and female flowers were open at the wrong times for each other. Recently there has also been a reduction in the number of bees which has affected lots of crops. Flowers just aren't getting pollinated enough. The bees have been dying from a mite. If you need to you can pollinate the female flowers, by taking a male flower and removing its petals, then rubbing it on the inside of the female flower. Sometimes plants fail to pollinate when it is too hot or too cold. Sometimes heavy rains will make it impossible to for the bees to do their job when the flowers are ready. Also, sometimes really odd things happen. I had one year where all my zucchini plants only produced male flowers. The other squash flowered normally. Sharon gordonse@one.net