i am getting the error while login with login control

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C#

ASP.NET

SQL

My problem is related to c# and SQL server express 2008. i am performing functions on the live server.. my application is working fine with the live server, i am able to fetch and display data from the server into my website.. the only problem which i am having is while login with login control. i am getting the following error while login..

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)

Source Error:


Line 26:         if (string.IsNullOrEmpty(Request.QueryString["ReturnUrl"]))
Line 27:         {
Line 28:             if (Roles.IsUserInRole(Login1.UserName, "admin"))
Line 29:                 Response.Redirect("~/admin/add-product.aspx");
Line 30:             else

i have written code on logged_in event of login control like below


        if (string.IsNullOrEmpty(Request.QueryString["ReturnUrl"]))
        {
            if (Roles.IsUserInRole(Login1.UserName, "admin"))
                Response.Redirect("~/admin/add-product.aspx");
            else
                Response.Redirect("~/ProfileInfo.aspx");
        }


i am not able to understand what's the problem.. because i am free to perform any other function..

One more thing when i connect from local host with the live server then it works fine...


My web config file is like below..

<location path="admin">
  <system.web>
    <authorization>
      <allow roles="admin" />

      <deny users="*"/>
    </authorization>
  </system.web>
</location>
<system.web>