Why am I getting an error with Reporting Services Add-in for Sharepoint products?

Question

Background:

I deployed reporting services in a sharepoint integrated mode, installed add in and configured reporting services in MOSS, everything is done fine, I am using NTLM authentication, so I replaced the RSWindowsNegotiate with RSWindowsNTLM in the rsreportserver.config file and stepped out from the problem in authorization in Manage Integration Settings part, I faced an error with Grant Database Access and also stepped out from by using some lines of code that grant permission to the reporting services service account to sail through all the web application in my sharepoint.

Problem:

When I added the report viewer web part and went to browse the site to add a report stored in a document library in my site I got the following error:

The request failed with HTTP status 401 : unauthorised

Answer 1

Maybe You receive an "HTTP Error 401.1 - Unauthorized: Access is denied due to invalid credentials" error message when you try to access a Web site that is part of an IIS 6.0 application pool

When you try to access a Microsoft Internet Information Services (IIS) 6.0 Web site that is configured to use Integrated Windows authentication only, you are prompted for your user credentials. When you try to log on, you receive the logon prompt again. After you try to log on three times, you receive the following error message:

HTTP Error 401.1 - Unauthorized: Access is denied due to invalid credentials.

...

1. Start a command prompt.
2. Locate and then change to the directory that contains the Adsutil.vbs file. By default, this directory is C:\Inetpub\Adminscripts.
3. Type the following command, and then press ENTER:

cscript adsutil.vbs set w3svc/NTAuthenticationProviders "NTLM"

1. To verify that the NtAuthenticationProviders metabase property is set to NTLM, type the following command, and then press ENTER:

cscript adsutil.vbs get w3svc/NTAuthenticationProviders

  The following text should be returned:

NTAuthenticationProviders       : (STRING) "NTLM"