webring

hi there.
i run a small scale web directory. when ever a user adds his/her site to my directory oi send tham a small email "your link has been added" sort of thing. I also set up a webring last week and offered my users the chance to become part of the webring.... all they do is click on a link from the email. fill in a few fields and i either eccept or decline the offer. The bigest problem is a lot of people like the idea and sign up...but not so many actualy paste the code in their pages...in effect i am sebding out traffic and most members are also sending out traffic but there are a few who simply refuse to paste the code.... how long should i let this go on. i know it sometimes takes time to paste code in pages but it is unfare to members who abide ny the rules. what would you do in a situation like this???