If they are inside, have you polinated them? I use an artist paint brush. Cucumbers have both male and female flowers.

I also act like a bee by buzzing around with a soft artists brush doing the job a bee does with success.

I've done that several times and the little cucs start to grow. But they never get longer than 1". It seems the plan is putting all it's energy into the flowers and not the fruit.

too much nitrogen.