Cannot Change Password From OWA

Hi,
Iam not able to chnage the password from OWA 2000.
I have Windows 2000 with service pack 2 and MS Exchange 2000 .
When i open OWA and and click on options and then click on “Change Password”.
It bring’s up a new internet window and give message. “The page cannot be displayed.”
If any body need any other information let me know.
Regards
Mudassir