The ZoneDirector is really meant to be used with premium support -- and in fact firmware 9.9 and above have started enforcing this -- if you do not have a premium support entitlement, it will not let you update the firmware anymore.
You should consider purchasing a support contract to use with your ZD (they aren't even sold new without a 1-yr support contract).
Yup. We did purchase 3 years premium support and I did register the licenses but when I tried to download the firmware, it said I didn't have the premium support. It turned out that the system didn;t like Firefox and when I used Chrome, it downloaded whcih seems weird. Thanks for your help.