A campaign might not serve any impressions after it launches for multiple reasons:
The Campaign or Creative Sets Are Paused
A campaign can serve impressions only if both the campaign and at least one creative set are enabled.
To enable a paused campaign, go to the Campaigns page in the dashboard and toggle the campaign’s toggle to green (on).
To enable a creative set, click one of the campaigns, locate its toggle, and toggle it to green (on).
The Campaign Shell Is Configured Incorrectly
The Campaign Launch Dates Are Incorrect
If the campaign start date is set in the future or the end date is set in the past, the campaign may not serve any impressions.
You Have Insufficient Prepay Account Balances
Examine your prepay account balance.
Campaigns do not serve if the available account balance is less than the live campaign budget for the day.