Unable to renewal Windows 2012 RDS Certificate.

On my Windows 2012 RDS connection broker server, I created a cert request in IIS.  After I received the cert from my vendor, I completed the cert request and applied the new cert to the RDS website.  

I then go to MMC and export the certificate to a PFX file with a password.  

Next, I go to Server Manager>RDS>Overview.  Under Deployment Overview, I go to edit Deployment Properties>Certificates.  I highlight the "RD Connection Broker - Enable SSO" and select existing certifiate.  

I specify the cert I export and the password and I get the attached error.  

Please advise if you know how to fix it.