How to renew a certificate using Microsoft Active Directory Certificate Services

I'm using Microsoft Active Directory Certificate Services to request certificates and also download them when they are issued by the administrator.

I've got a bunch of certificate expiring and I want to renew them using the web application and I got the following option:

Submit a certificate request by using a base-64-encoded CMC or PKCS #10 file, or submit a renewal request by using a base-64-encoded PKCS #7 file (http://iis-server/certsrv/certrqxt.asp)

I converted my expiring certificate from CER to P7B in order to submit a renewal request.

But I keep on getting this error:

Error Parsing Request The signed cryptographic message does not have a signer for the specified signer index. 0x8009200e (-2146885618)