knee leash on a wetsuit???

I've just bought a longboard and I decided to get a knee leash to avoid tripping all over it (thinking way ahead like someday I'll be able to noseride
). The problem is, it's making my wetsuit frey (is that the word???). I've used it for a week solid and on my wetsuit around the back of my knee it's gone all weird like the leash is chaffing and wearing out the wetsuit. What should I do? Are these leashes designed for warmer climates where you don't wear a wettie? Should I get a normal leash? Should I bother trying to take the other one back (bearing in mind it's in a state now). I don't want it to damage my wetsuit which cost a fortune!

