用户.IsInRole不能在服务器上工作

我使用的是ASP。。NET 2012, SQL Server 2008和c#为我的网站。当我执行以下代码时:

if(User.IsInRole("Admin"))
    Response.Redirect("test.aspx");

在Default.aspx.cs和运行在Visual Studio本地没有错误。在部署我的网站并尝试使用Admin Role中的用户登录后，服务器上出现以下错误:

时发生与网络相关或特定于实例的错误建立到SQL Server的连接。未找到服务器或无法访问。验证实例名是否正确SQL Server已配置为允许远程连接。(供应商:SQL网络接口，错误:26 -定位服务器/实例错误指定)

我的ASP。. NET成员数据库位于主机上。我应该在Default.aspx.cs使用连接字符串吗?如果是，我该如何写呢?

我确定我登录的User在Admin Role中。

web.config:

<configuration>
  <appSettings>
    <add key="ValidationSettings:UnobtrusiveValidationMode" value="None"/>
  </appSettings>
  <connectionStrings>
    <add name="MembersConnectionString" 
         connectionString="workstation id=mssql;packet size=4096;user id=shahi_SQLLogin_1;pwd=password;data source=mssql;persist security info=False;initial catalog=akhbarrr" />
    <add name="SabteAKhabar" 
         connectionString="workstation id=mssql;packet size=4096;user id=shahi_SQLLogin_1;pwd=password;data source=mssql;persist security info=False;initial catalog=akhbarrr" />
    <add name="ConnectionString" 
         connectionString="workstation id=mssql;packet size=4096;user id=shahi_SQLLogin_1;pwd=password;data source=mssql;persist security info=False;initial catalog=akhbarrr" />
    <add name="akhbarrConnectionString" 
         connectionString="workstation id=mssql;packet size=4096;user id=shahi_SQLLogin_1;pwd=password;data source=mssql;persist security info=False;initial catalog=akhbarrr"
         providerName="System.Data.SqlClient" />
  </connectionStrings>
  <system.web>
    <customErrors mode="Off">
      <error statusCode="403" redirect="access.aspx"/>
      <error statusCode="404" redirect="nofile.aspx"/>
    </customErrors>
    <anonymousIdentification enabled="true"/>
    <profile enabled="true" defaultProvider="AspNetSqlProfileProvider">
      <properties>
        <add name="FirstName" allowAnonymous="false"/>
        <add name="LastName" allowAnonymous="false"/>
        <add name="AkharinMadrak" allowAnonymous="false"/>
        <add name="Reshte" allowAnonymous="false"/>
        <add name="Gerayesh" allowAnonymous="false"/>
        <add name="NahveAshnayi" allowAnonymous="false"/>
        <add name="Address" allowAnonymous="false"/>
        <add name="PostalKod" allowAnonymous="false"/>
        <add name="City" allowAnonymous="false"/>
        <add name="Town" allowAnonymous="false"/>
        <add name="Number" allowAnonymous="false"/>
        <add name="BirthDay" type="System.DateTime" allowAnonymous="false"/>
      </properties>
    </profile>
    <authorization>
      <allow roles="Managers"/>
      <allow roles="Admin"/>
      <allow roles="AdminAsli"/>
    </authorization>
    <authentication mode="Forms">
      <forms timeout="5" cookieless="AutoDetect" protection="All"/>
    </authentication>
    <membership defaultProvider="SqlProvider" userIsOnlineTimeWindow="15">
      <providers>
        <clear/>
        <add name="SqlProvider" type="System.Web.Security.SqlMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" connectionStringName="MembersConnectionString" applicationName="MyApplication" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" passwordFormat="Hashed"/>
      </providers>
    </membership>
    <roleManager enabled="true"/>
    <pages validateRequest="false" enableEventValidation="false" viewStateEncryptionMode="Never" enableViewStateMac="false"/>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Extensions.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
        <add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
        <add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
      </assemblies>
    </compilation>
    <httpRuntime/>
    <machineKey validationKey="1234567890123456789012345678901234567890AAAAAAAAAA" decryptionKey="123456789012345678901234567890123456789012345678" validation="SHA1" decryption="Auto"/>
  </system.web>
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false"/>
    <handlers>
      <add name="MSCaptcha" path="CaptchaImage.axd" verb="GET" type="MSCaptcha.CaptchaImageHandler, MSCaptcha" preCondition="integratedMode,runtimeVersionv2.0"/>
    </handlers>
  </system.webServer>
  <system.net>
    <mailSettings>
      <smtp from="xxxxxx@gmail.com">
        <network host="smtp.gmail.com" password="xxxxxx" port="587" userName="farzanehsd@gmail.com" enableSsl="true"/>
      </smtp>
    </mailSettings>
  </system.net>
</configuration>