404 error when using Web Service

I'm building a client application that uses the SSRS Web Service. My problem
is that when I use the servername the web service works just fine. ie
http://RServer/ReportServer/reportservice.asmx
If I try to use the full DNS name of the server any call I make to the web
service returns a 404 error.
ie if I use http://RServer.sdm.dm.com/ReportServer/reportservice.asmx which
points to the same server gives me a 404 error..I've looked at the config
files for ReportServer and can't figure out what's going wrong...
Any help would be greatly appreciated..
Thanks
JasonHello Jason,
To use the FQDN name of the report server, please check the ReportServerUrl
element in the RSWebApplication.config file.
You need to specify the FQDN name for this element. Please refer this
article:
RSWebApplication Configuration File
http://msdn2.microsoft.com/en-us/library/ms155878.aspx
Hope this helps.
Sincerely,
Wei Lu
Microsoft Online Community Support
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==================================================This posting is provided "AS IS" with no warranties, and confers no rights.|||Hi ,
How is everything going? Please feel free to let me know if you need any
assistance.
Sincerely,
Wei Lu
Microsoft Online Community Support
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400: Bad Request

I am getting an "The request failed with HTTP status 400: Bad Request " Error in Report Manager Webpage. http://servername/Reports
The Reportserver itself and reports works fine (http://servername/reportserver).
Reports render OK and i am still able to connect to reportserver by management studio.

The environment is a W2K3 Standard with SQL 2005 (Build 2153) - and the server is a domain controller.

Reporting Service Configuration does not mention any issues - I have reapplied default settings - no change.
There are no errors in the eventlog.

I need some help - please

HANNESI have already checked the following posts

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=284929&SiteID=1
(I did not understend the "RSWebApplication.config" file - as soon as i write in the a reportserver url the website returns an execption - so this config must be empty I guess)

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=479636&SiteID=1|||This post gave me the finale hint (http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=165851&SiteID=1) - but I do not habe a specific IP address bound to the website - but I had specific hostheaders and it seems the reportmanager needs at least one binding with no hosthader in my environment - therefor I added a fifth binding with no hosthander, no specific IP and default Port

Hannes