The first thing to check is where you have your cucumbers planted. Cucumbers need full, bright sunlight to produce fruit. If this is not the problem take a look at your fertilizer. A fertilizer high in nitrogen can cause the plants to produce more foliage than cucumbers.
Another key to getting cucumbers to produce is pollination. Pollen must be transferred from the male to the female flower in order to produce fruit. You can distinguish a female from a male because the female has a tiny cucumber at the base of the petals. The plant will produce about 10 to 20 male flowers for every female flower. Blooms are only open for a day.
Bees are elemental in the pollinating process. They transfer pollen from male to female blooms. So, if your bee activity is low then your cucumber production will also be low. Cold temperatures and rain reduce bee activity. Over use of insecticides is also detrimental to bees. If you must use an insecticide, do so sparingly and only in the afternoon when bees are less likely to appear.