Need help. I work with Leadimpact. And get empty subids in 50% or more cases.

I work with leadimpact (IE browsers with toolbars). They show a popup with my Landing page. On my landing page is placed a button - CLICK HERE. Code is a href="offer.php" target="_blank" When I use this code a href="offer.php" - everything is working 100% good. But when I use target="_blank" - prosper202 goes crazy, and I get empty subids to my CPA account. I placed my own php code on offer.php to track referers and ips etc. &pci= - is empty, referer is empty!

I think that target="_blank" is causing a problem. Have you noticed this problem?

I started to investigate in Google. And it seems that IE browser resets session, cookie etc sometimes when you click and open something in a new window. Maybe I'm wrong...