Login failed for user '(null)'. Reason: Not associated with
a trusted SQL Server connection

I dont believe that no one can help me in this damn error,

Please, I'm gonne lose my job offer If I didnt fix this. I have spent 7 days
searching with no use !!

I use ASP.NET 2.0 with C# to develop an intranet site, it was working perfectly
when i was on Visual Studio, when i tried to publish the site it gave me that
error.

Login failed for user '(null)'. Reason: Not associated with a trusted SQL Server
connection.

the web application on IIS server, windows 2003 - the database on a different
server windows 2003, sql server 2000.

Regaeding that we have proxy server, one firewall.

I tried to do the following steps with no use :(

1. Create a Domain Account with priveleges similar NETWORKSERVICE (windows
server 2003).

2. Grant this Domain Account (DomainName/NETWORKSERVICE ) access in the SQL
Server Database for the necessary databases (created a new login for this user
and gave it the privillage creator, read, write)

3. <identity impersonate="true"
userName="DomainName\UserName" password="password" />

The second method is to simply set identity impersonate to true and assign the
username and password in the IIS.

1. Type inetmgr from your command prompt and give enter.

2. This would open the IIS Control Panel.

3. Expand the appropriate nodes and select the Virtual Directory of your
application.

4. Right Click and select Properties.

5. Switch to the Directory Security Tab.

6. Under Anonymous access and authentication control click Edit

7. Check the Enable Anonymous access in case you want people to access the
application without logging in with Windows Logon Screen.

8. Uncheck the Allow IIS to control password and enter the DomainName/UserName
and Password in the respective boxes. Usually IIS uses IUSER_MACHINENAME
credentials for Anonymous access.

9. Uncheck if any other authentication mode is checked

I did the previous step exactly like that. and the error still come.
I remind you again we have a proxy server with one firwall
I dont running under https X

My connection string is:
    <add name="LocalSqlServer" connectionString="Data
Source=database server IP; Initial Catalog=database name; Integrated
Security=True"; UID="sa" ; pwd="password";
      providerName="System.Data.SqlClient" />
Please find me a solution

Check out this post:
http://geekswithblogs.net/ranganh/archive/2005/05/25/40489.aspx

I did exactly what said in this article, and still the error arise