Dear Abhishek, for AIIMS MBBS, the age eligibility is that you should be atleast 17 years old on or before December 31st, 2019. And you will be 18 years by December 31st, 2019. I wonder why it shows that you don't fill the age criteria because you fufill the age criteria. I would suggest you to retry lest it is a technical error. If the problem persists, please reach out to their helpline at aiims.mbbs18@gmail.com.