Commercial Certificates - Zimbra :: Wiki

I used this procedure earlier this year to create the key and certificates for the non-java services on our ZCS 4.5 server. The certificate will expire Tuesday. I successfully installed the new certificate for Java, but I'm failing at getting the key out of the keystore. It's extremely frustrating. Here's the error:

zimbra01:~ zimbra$ java ExportPriv /opt/zimbra/ssl/ssl/commercial.keystore tomcat zimbra > my.key
Exception in thread "main" java.lang.NullPointerException
        at ExportPriv.doit(
        at ExportPriv.main(
How can I overcome this error and recreate the necessary .key and .crt files for /opt/zimbra/conf/?