No Fruit on Melon and Cucumber Plants

My melon and cucumber plants appear healthy, but there is no sign of fruit. The blossom forms, falls off, but no fruit forms.

The first set of flowers that form on vine crops are all male (straight stem only stamen). The second set of flowers has both male and female (a swollen base like a miniature melon or squash) flowers. Be patient. Once the plant has both male and female flowers the bees will have something to pollinate. Fruit will start developing soon after this. Then you will have more cucumbers and squash than you can use.