Grand Master Pabris:
To become a Human Knight, you need the appropriate level and token. Your level must be at least 20 to qualify to change profession. To become a Knight, you need a token to prove you have passed the Test of the Human Knight, as well.
It seems that you have admirably passed the Test of the Human Knight, but your level is not high enough. Level 20 or higher is required to change profession. I cannot allow you to change profession if your level is not sufficient, even if you have a token. Come back when you have raised your level.