Fistula or graft after transplant.

So here's the deal, I received my Transplant on Jan. 8th of this year. I have a fistula in my left wrist, about 2 inches above that they had to replace my vein with tube. The fistula is still purring like a kitten, but the graft there is nothing. The tube is actually flat in shape. Above the graft there is a pulsejust like there should be. We first noticed something wrong in in March when I had to do plasmaphersis(sp), They were going to use it to do the treatment, but there was nothing there. Now it seems like every other vein in my hand is purring. My veins in my left arm looks like Arnolds. Now they have never done a fistulagram, but they say it's not clotted off because i have a strong pulse above the graft in my elbow. So I'm just wondering "how is the fistula feeding all the other veins in my arm.