Failed experiment

On her blog, Belinda created some gorgeous wax paper resist backgrounds using only regular card stock, not glossy card stock. Since I don't have any glossy, I've never tried this technique, but Belinda gave me the courage to do so when she experimented with plain old regular card stock (cs).

What you do is sandwich crumpled wax paper between two sheets of cs, then sandwich this assembly between two heat resistant craft sheets and iron. What could be more simple, right? Well, as you can see on Belinda's blog, she got lovely spidery effects with hers and I got practically NOTHING.
I'm hoping someone who reads my blog will have an answer as to why Belinda's technique worked and mine failed. I didn't press and leave my iron, but kept it moving slowly over the piece. My iron was set on "cotton." When I removed the waxed paper, I could see the little spiders on both sides of the paper, so I know I got good coverage. However, when I colored them, they didn't show any spidery effects, just little "blobs." I used pigment ink to color my pieces. I used the direct to paper technique and swiped the pigment ink over the paper, attempting to blend as I changed ink pads.
Possible reasons for failure include:
1) I ironed too long
2) I didn't iron long enough
3) My iron was too hot
4) Pigment ink doesn't work
5) Something totally different I haven't considered

Please let me know if you have tried this technique and what I did wrong. Belinda suggested it might be because I used pigment instead of dye ink.