Activesync exchange server 2007 server 2003

I'm trying to get activesync configured and I keep getting errors when testing using microsoft remote connectivity analyzer.

      ExRCA is testing Exchange ActiveSync.
       The Exchange ActiveSync test failed.
       
      Test Steps
       
      Attempting to resolve the host name mail.ghcontractinginc.com in DNS.
       The host name resolved successfully.
       
      Additional Details
       IP addresses returned: 216.16.201.14
      Testing TCP port 443 on host mail.ghcontractinginc.com to ensure it's listening and open.
       The port was opened successfully.
      Testing the SSL certificate to make sure it's valid.
       The SSL certificate failed one or more certificate validation checks.
       
      Test Steps
       
      ExRCA is attempting to obtain the SSL certificate from remote server mail.ghcontractinginc.com on port 443.
       ExRCA successfully obtained the remote SSL certificate.
       
      Additional Details
      Validating the certificate name.
       The certificate name was validated successfully.
       
      Additional Details
      Validating certificate trust for Windows Mobile devices.
       Certificate trust validation failed.
       
      Test Steps
       
      ExRCA is attempting to build certificate chains for certificate CN=mail.ghcontractinginc.com.
       A certificate chain couldn't be constructed for the certificate.
        Tell me more about this issue and how to resolve it
       
      Additional Details
       The certificate chain didn't end in a trusted root. Root = CN=mail.ghcontractinginc.com


Please help!!