Server Certificate objects created for use with an external CA will display this screen when they do not yet have Public Key or Trusted Root certificates associated with them. When you receive a certificate from the external CA, you must manually install it into the Server Certificate object. This is done by using the Import Certificates button. The Import Certificates button is available from the General tab or the Certificates tab.
Import Certificates
This button will allow you to import a Trusted Root certificate and a server certificate into a Server Certificate object. If you do not have a trusted root certificate, you can indicate it. Also, if a trusted root already exists in the Server Certificate object, you can specify to keep the existing trusted root certificate.