Cucumbers? ? ?

I have several cucumber vines, two outside, two in pots on a sunny balcony. They are all growing well, and are now 5 feet long.
They all have loads of blooms -- but no cucumbers. The cucumbers may reach an inch in length, then just stall.
What gives?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.