This can be due to one of the following:
Some websites receive such a large amount of impressions - millions of page views per month - that it is almost impossible to actually see your ad at any one time on the site, even with refreshing many times.
Some websites use an ad manager to rotate between BSA ads and ads from another network - so your ad will not be seen during every page refresh. You will still receive the impressions estimated for your ad, but you won't see your ad on every page refresh.
Make sure you are looking in the correct location on the site. Some ad zones are specific to certain sections of a website. The website owner will usually describe the zone location in the description of the zone you purchased. If in doubt, please open a support ticket and we can look into this for you.
If the impression count in your dashboard seems to be much lower than it should be for your ad, or if you notice a sudden drop in impressions in the results graph, it may be that the zone code was accidentally removed from the website. If you think this is the case, please open a support ticket and we will try to get in touch with the publisher to resolve this as soon as possible. If the publisher can fix this quickly, and your ad is displayed again, we will extend your campaign to make up for the lost time. If for some reason this cannot be resolved with the publisher, then a refund request will be submitted for the ad.
We tend to answer most support tickets during normal business hours: Monday to Friday, 9:00 am to 6:00 pm (EST). However, we're constantly monitoring tickets, and we'll address urgent issues on nights and weekends, too.
Open a Ticket