When you see click-through activity but no impression activity, it means that we are tracking your referrals, but not the number of times your link is being displayed on your site. There are various reasons why this can happen. Two common reasons are:

1. You did not copy and paste the entire link code as provided in your Publisher Dashboard. In cases where the image in a banner link is served by a third party or the link is text-based, we add a 1x1 pixel to the code. This 1x1 allows us to track impressions. If it is removed, then we cannot track associated impressions.
2. You have downloaded the image in a banner link and are serving the image directly from your own servers. If we do not serve the image, or a 1x1 pixel code is not included in the code, we cannot track impressions.