Pumpkins Vining Up A Weed?

Well, I planted these pumpkin seeds in late Spring (I live in northwest Ohio) and the vines have grown pretty long and thick so far with orange blooming flowers though they don't seem to be producing actual pumpkins. Now there were a bunch of tall Ragweeds growing right next them that they were using to vine up but I decided it was getting too crowded so I cut the weeds down.

But now I'm afraid this may be the reason why their not producing fruit because I interrupted their vining habitat. I did leave some Ragweeds in place and put up a small wire fence for them to vine, but they seemed to stay put on the ground instead of vining up the wire fence.

So did I just delay my pumpkins production or is there another reason the fruit hasn't come yet?

Sidenote: I just discovered a good use for mature Ragweed plants.

Well, they were probably better off vining, but I don't know whether or not that would have delayed fruiting.

Kellic,

My pumpkins are fruiting just fine trailing on the ground. I doubt that can be the cause of not setting fruit, except maybe if the surrounding weeds are so high pollinators can't see the flowers... 

Are you not getting female flowers or are they not getting fertilized?
1st case: often happens with cucurbits, be patient, the females should arrive soon
2nd case: not enough pollinators available, pollinize by hand

Well, maybe they haven't been pollinated yet. Usually its September or even october before pumpkins truly appear so I'll be patient.

Now there vining again on the trellis and fence.