Unable to Enroll For NSE 2 certification program.

Hi All,   I completed NSE 1 course and received the NSE 1 certificate. Now I want to enroll for NSE 2 but I'm getting the message "You do not have permission to self-enroll.". Is NSE 2 & above only for Fortinet partners & employees?    I want to complete NSE 4, kindly let me know how to enroll for NSE 2 so that I can progress further.