Zone probabilities

The Zone properties > Probability tab lists all banners currently considered for delivery in a zone. To change the likelihood of delivering a banner, change the priority level of the campaign or change the weight of the banner.
Important: These changes not only affect this zone but all zones linked to the banner or campaign.

If no banners are currently considered for delivery, the list will be empty unless the zone is chained with another. If a chain is set, the list can contain banners that are not linked to this zone but are likely to be shown.
See also: Campaign priority level, Banner weight and Zone chaining.