There could be a number of reasons why your campaign may not be getting traffic:
* Account Balance (Is your campaign below our threshold of $25.00?).
* Campaign Budget Reached.
* Blocked Ad Attribute or Vertical.
* No Creatives Online For Specific Ad Size.
* Retargeting Audience Too Small.
* Limited of Impressions Available for Geo Location.
* Limited of Impressions Available for Banner Sizes.
* Campaign is Running Outside date range selected.