I had a similar problem and tried to use HTTP_REFERER to get around it, but it didn't work. In the end, I came up with this:
put this in your ad forwarding page:
if ($_SERVER['QUERY_STRING'] == 'realthing=true') {
//
}
else {
echo ("You cannot access this page. You have to click our image first!");
exit;
}
when your image/text links to the add forwarding page, instead of:
<a href="adforwardingpage.php">adforwardingpage</a>
use <a href="adforwardingpage.php?realthing=true">adforwardingpage</a>
It's not perfect, but it works for me, I hope it helps you out too.
