HTTP 500 trouble to get users in DirectPush technology

Hello experts,
I wish someone can assist me troubleshoot this. On our exchange server 2003, I have faced a constant HTTP 500 trouble to get users in DirectPush technology. Here I am giving a number of hardware background information:
Front-End server:
Exchange 2003 SP2 with Windows Server 2003
Back-End Server:
Exchange 2003 SP2 with Windows Server 2003
We tried to follow these articles:
Deleting and recreating Microsoft-Server-ActiveSync in IIS
http://hardware.mcse.ms/archive35-2005-12-262517.html
Problems in Synchronizing a Pocket PC with Exchange Server 2003 when using SSL and Forms-Based Authentication in OWA
https://www.petri.com/problems_with_forms_based_authentication_and_ssl_in_activesync
And ..
How did we setup our Exchange for OWA, OMA, ActiveSync and RPC over HTTPS
http://www.howtonetworking.com/email/oma1.htm
But we still get the problem… The accurate event ID error is the common:
Event Type: Error
Event Source: Server ActiveSync
Event Category: None
Event ID: 3005
Date: 3/21/2006
Time: 10:02:53 AM
User: XXXYYY
Computer: FRONT-END
Description:
Unexpected Exchange mailbox Server error: Server: [XXX.XXX.XXX] User: [[email protected]] HTTP status code: [400]. Verify that the Exchange mailbox Server is working correctly.
I know this has been conversed before but it looks that all accessible options are not working. I almost required to calling MS, but hopefully you can give the proper answers.
Need a solution to solve this. Please help. Thanks.
