How To Buy Stumbles From Stumbleupon NOT

Being that stumbleupon was the single biggest referer of traffic in January I thought I would buy some more stumbles and report on what I found. So far I have found buying stumbles from stumbleupon is not easy... in fact I have found it impossible. Its hard to even find the signup link but its here - http://www.stumbleupon.com/ads/ First of all its hard to find out where you can even do it. I found the url I have 20 different urls and no matter what I choose I get :

From: StumbleUpon Ads Date: February 27, 2007 8:02:21 PM CST To: jeremy@shoemoney.com Subject: Ad Not Approved Reply-To: StumbleUpon Ads $siteurl was not approved because there is currently an insufficient number of people on StumbleUpon who will appreciate your site. Please feel free to submit others sites for approval. -- StumbleUpon Ads

So anyone had any luck or can give me any tips ? =P