hi
my portal instal on server
when i add the Ropository module to the page
I visit this error ?

A critical error has occurred.
A network-related or instance-specific error occurred while
establishing a connection to SQL Server.
The server was not found or was not accessible.
Verify that the instance name is correct and that SQL Server
is configured to allow remote connections.
(provider: SQL Network Interfaces,
 error: 26 - Error Locating Server/Instance Specified)

what can i do?

connectionStrings> Connection String for SQL Server 2005 Express --> Connection String for SQL Server 2000/2005-->add name="SiteSqlServer" connectionString="Server=******;Database=******;uid=******;pwd=******;" providerName="System.Data.SqlClient" />connectionStrings>appSettings> Connection String for SQL Server 2005 Express - kept for backwards compatability - legacy modules -->add key="SiteSqlServer" value="Data Source=.\SQLExpress;Integrated Security=True;User Instance=True;AttachDBFilename=|DataDirectory|Database.mdf;" /> Connection String for SQL Server 2000/2005 - kept for backwards compatability - legacy modules-->add key="InstallTemplate" value="DotNetNuke.install.config" />add key="AutoUpgrade" value="true" />add key="UseInstallWizard" value="true" />add key="InstallMemberRole" value="true" />add key="ShowMissingKeys" value="false" />add key="EnableWebFarmSupport" value="false" />add key="EnableCachePersistence" value="false" />add key="HostHeader" value="" /> Host Header to remove from URL so "www.mydomain.com/johndoe/Default.aspx" is treated as "www.mydomain.com/Default.aspx" -->add key="RemoveAngleBrackets" value="false" />optionally strip angle brackets on public login and registration screens-->add key="PersistentCookieTimeout" value="0" />use as persistent cookie expiration. Value is in minutes, and only active if a non-zero figure--> set UsePortNumber to true to preserve the port number if you're using a port number other than 80 (the standard)-->add key="InstallationDate" value="3/12/2009" />appSettings> 

<!--

<add

name="SiteSqlServer"

connectionString="Data Source=.\SQLExpress;Integrated Security=True;User Instance=True;AttachDBFilename=|DataDirectory|Database.mdf;"

providerName="System.Data.SqlClient" />

<!--

<

</

<

<!--

<

<!--

<add key="SiteSqlServer" value="Server=(local);Database=DotNetNuke;uid=;pwd=;"/>

<

<

<

<

<

<

<

<

<!--

<

<!--

<

<!--

<!--

<add key="UsePortNumber" value="true" />

<

</

I'm sorry but

i changed it :

but now when add repository on a page :
A critical error has occurred.
Invalid value for key 'attachdbfilename'. 

i forget say that my portal (dnn 4.09.00) and install on server (not local)