If one of your line items isn't delivering ads, please review the following troubleshooting tips:
Have the order and line item been approved?
Have you confirmed the status of your line item?
A line item’s status will change from 'Ready' to 'Delivering' when it has begun delivering valid impressions. However, impressions discarded because of invalid activity will not affect the status.
Has sufficient time passed for the change to take effect in the server?
If not, review your line item's flight dates by clicking the Orders tab, then click the order containing your line item. Your line item's flight dates will appear as the start and end dates.
Have you overbooked the line item? If you're attempting to deliver more impressions than you have, not every line item will serve. See Line item is overdelivering or underdelivering for more information.
Are any creatives associated with the line item? If a line item has more than one size assigned to it, it will be eligible to serve as soon as a creative with a matching size is uploaded.
Targeting and contending line items
Have you properly tagged your pages? Try using one of the following diagnostic tools:
If you're using DART ad tags on your website, you can use the DFP TagShooter to see which ads are eligible to serve to that ad request, or why your ad isn't serving to a particular request.
If you're using GPT ad tags on your website, you can use the on-screen debugging tool called the Google Publisher Console to troubleshoot your ad tags.
Does the ad tag contain the custom criteria that the line item is targeting?
To review your line item's targeting criteria, click the Inventory tab, then click Targeting.
Does another line item conflict?
Line items may not serve ads if another line item takes priority or is behind schedule. You can find out what ads are competing by examining the list of ‘Delivering’ line items on the 'Orders' tab.
If the problem is with a third-party creative, see Third-party creative isn't delivering for troubleshooting steps specific to that creative type.