Hi and welcome to the community. You may have reached a cap for your region. The topic below has some information that might help explain. Also, posted the link to the ad catalog viewer. You can check if ads are still available for your region and if you are eligible to receive them.
If it some other issue, you will need to provide more information. Just not enough information to help. The link below is to the Rewards/Ads template. If you could follow the instructions, read the articles, and if you still have an issue, edit your post, copy and paste the template, and answer the questions.