Certain types of ads are eligible to appear only on certain websites. For example, image ads and display ads may only appear on the Display Network, not on search results pages, and only on sites whose owners have opted in to those ad types. Similarly, mobile ads will only show on WAP mobile devices.
The Ad Preview and Diagnosis tool currently only supports diagnosis for ads appearing on search results pages, so if your ad group only contains ads that may only show on the Display Network, you may receive feedback that your ads aren't showing, even as they continue to accrue impressions.
If you would like your ads to show on search results pages, create a text ad.
Learn more about ad types and about optimizing your campaign for maximum visibility.
