Hello Madhan,
Thank you for contacting us. Since you're able to load test ads, then it is safe to assume to that your implementation is good. If it's a newly created Ad Unit ID, please note that it might take few hours to start serving ads. If you're still not able to load the ads, please share your Ad Unit ID, so I can take a look. You can reply back via Reply privately to author option.
Regards,
Bharani Cherukuri
Mobile Ads SDK Team