To test the online responder, you can create a new computer certificate. After you have exported this certificate to a CER file run certutil –URL c:\temp\MyCertificate.cer. This command opens the window.
Select OCSP and click Retrieve. The status of this certificate should change to Verified. Now you can revoke this certificate on your CA and publish the CRL again. If you now, click again on Retrieve the status should change to Revoked.