still can't grow pumpkins - what am i doing wrong?

What's actually going wrong, lots of flowers and no fruit, or the plants dying off mid-summer? No fruit is usually pollination. The first flowers are all male, the females (tiny pumpkin behind the petals) come later. If few bees are around, take a small brush in the morning and move pollen from a male flower to a female one. Other usual suspects: under 6-8 hours of sun, too much nitrogen fertiliser (huge leaves, no fruit), and if a vine suddenly wilts while the soil is wet, look at the stem base for a hole and sawdust-like mess. That's squash vine borer.