We're always working on new ways for you to get quality ad inventory, as well as developing safeguards to ensure that the conversions generated on publisher sites are valid. As you may know, referral ads are paid on a conversion basis; a conversion is considered a specific action defined by the advertiser. That action might be a sale, a clickthrough to a specific page on an advertiser site, or an online sign-up for a promotion. We've recently made a change to help make sure that the conversions generated by referral ads are valid. For some publishers who display referrals for non-Google products, the earnings you receive for the ad may now be less than the maximum referral value displayed for that ad. This is because our system will initially place a restriction on referral earnings as we monitor click and conversion data to determine that the conversions generated are valid. Once this validation period ends, you'll begin earning the maximum value of the conversions as displayed in your account. We can't say precisely how long the validation period will last, but will make every effort to ensure that it's as speedy as possible. It will vary by publisher since site activity is different for everyone, and we anticipate that the majority of you will be minimally affected. However, advertisers will only be charged the maximum referral value once a publisher has completed the validation period. Our goal with this change is to ensure the long-term effectiveness of the referrals program for both publishers and advertisers. By increasing the value and quality of the referral network, we believe we'll attract more advertisers and provide more opportunities for you to earn.Posted by Eva Woo - AdSense Product Marketing