I just wired a friend's board and he had a Timefactor. We couldn't find a good way to make that sucker stick without taking the rubber pad off of the bottom.
Same with my DL4, Boss pedals and anything else with a rubberized bottom though...
I took the rubber off of mine as well. That was the only way I could make it work. I always recommend that you put the rubber bottom back in the box and keep it though, so it doesn't get lost.
Assuming that you are using industrial strength velcro from home depot or walmart, I had that problem with the digitech bad monkey. Solved it with a thin coat of of super glue first.