SCEP certificate enrollment with Windows server 2012

[YN]

Hi

I have a FGT300C v5.2.4,build688 and a Windows server 2012, and want to request a certificate for the FGT from the Windows server using SCEP.

I setup the SECP service in Windows 2012 following http://social.technet.microsoft.com/wiki/contents/articles/9063.network-device-enrollment-service-nd..., with all default settings.

It seems that the setup is working, since both the https://my.domain.com/certsrv/mscep_admin and the https://my.domain.com/certsrv/mscep webpages are accessible.

However, when I request the certificates in the FGT web GUI by providing the SCEP server URL, the Challenge Password and other information, the certificate status keeps showing PENDING.

I also referred to old threads such as https://forum.fortinet.com/tm.aspx?m=81711 and https://forum.fortinet.com/tm.aspx?m=113836, but still cannot fix my problem.

So how this issue can be debugged or fixed, many many thanks in advance.

Thank you again.

YN