It's possible to have unfilled impressions even if you have AdSense or Ad Exchange dynamic allocation enabled for your network. The following scenarios illustrate why you might see unfilled impressions in your network:
- Scenario 1: Neither DFP nor your dynamic allocation source (AdSense or Ad Exchange, depending on what your network is using) has an ad, so no ad is returned to the player.
- Scenario 2: A third-party host (usually a network) doesn't have an ad to return to the player.
- Scenario 3: DFP has an ad (hosted either by DFP or by a third party). However, at the time of the ad request, the ad is not successfully rendered. There are many possible reasons for the ad not rendering successfully, including the following:
- For third-party ads, there was a problem on the third party's side with returning the ad. For example, the third party's ad servers went down or were misconfigured.
- The user navigated away from the page before the ad started playing.
- A click-to-play player pre-fetched an ad, but the player was never clicked, so the ad was never displayed.
- The user's Internet connection or computer crashed just before the ad started playing.