Problem with my teacher benefits

I uploaded a work certificate and it keeps saying I can’t prove my work relationship. I am pretty sure that I only have this work permit that can clearly prove my working relationship, and the work permit issued later does not even have the date of issuance. Not all school work permits are the same as required, I really don’t know how to prove that I am a teacher…
And I used this certificate for the two previous approvals, I don’t understand why it can’t be done now