ERROR 406 while using simulation api from .net application

Pls Help me why I m getting below error
The remote server returned an error: (406) Not Acceptable.

URL : https://gw-fatoora.zatca.gov.sa/e-invoicing/simulation/compliance
{
“csr”:"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
S0tLS1FTkQgQ0VSVElGSUNBVEUgUkVRVUVTVC0tLS0tDQo=
}

Why I m getting Invalid OTP whereas just now i generated OTP

{
“csr”: “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”
}

Dear @sohrabus

Thanks for reaching out,

Can I kindly ask you to check and confirm if you are generating the OTP from fatoora/simulation portal and not fatoora/portal?

Thanks,
Ibrahem doud.