ASP.NET MVC3应用程序不能获取Appfabric创建的连接字符串

Question

当安装并配置Appfabric for Windows Server后，在IIS管理器的连接字符串里可以看到有ApplicationServerMonitoringConnectionString 和ApplicationServerWorkflowInstanceStoreConnectionString两个连接串，我有一个asp.net mvc3的应用程序，需要使用这两个连接字符串。但在有些机器上，可以取到，在有些机器上又取不出，不知是何缘故，谁能给个思路？ 下面是一些具体的信息：

Asp.net mvc3中取连接字符串的代码：

 public static string SqlPersistedDBConnectionString
        {
            get {
                if (string.IsNullOrEmpty(ConfigurationManager.AppSettings["ApplicationServerWorkflowInstanceStoreConnectionString"]))
                {
                    throw new Exception("ApplicationServerWorkflowInstanceStoreConnectionString is not config.");
                }
                return ConfigurationManager.ConnectionStrings["ApplicationServerWorkflowInstanceStoreConnectionString"].ToString(); 
            }
        }

web.config 配置文件内容：

<?xml version="1.0" encoding="UTF-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=152368
  -->

<configuration>
  
  <connectionStrings>
  </connectionStrings>
  
  <appSettings>
    <add key="webpages:Version" value="1.0.0.0" />
    <add key="ClientValidationEnabled" value="true" />
    <add key="UnobtrusiveJavaScriptEnabled" value="true" />
    <!---Custom settings-->
    <add key="PromotionName" value="Workflow" />
    <add key="HealthReportMode" value="All" /> <!---Simple or All-->
  </appSettings>

  <system.web>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      </assemblies>
    </compilation>

    <authentication mode="Windows">
      <!--<forms loginUrl="~/Account/LogOn" timeout="2880" />-->
    </authentication>
    <identity impersonate="false" />
    <anonymousIdentification enabled="false" />
    <membership>
      <providers>
        <clear />
      </providers>
    </membership>

    <profile>
      <providers>
        <clear />
      </providers>
    </profile>

    <roleManager enabled="false">
      <providers>
        <clear />
       
        <add name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/" />
      </providers>
    </roleManager>

    <pages>
      <namespaces>
        <add namespace="System.Web.Helpers" />
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Routing" />
        <add namespace="System.Web.WebPages" />
      </namespaces>
    </pages>
  </system.web>

  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
      <modules runAllManagedModulesForAllRequests="false">
          <remove name="RoleManager" />
      </modules>
        <security>
            <authorization>
                <remove users="*" roles="" verbs="" />
                <add accessType="Allow" users="" roles="Administrators" />
            </authorization>
        </security>
  </system.webServer>

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="3.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

我有两台服务器，都有相同的配置，但是一台能访问，另一台不能访问，不能访问的那台，之前都是可以的，但突然就不行了。

两台机器配置是：Windows server 2008 R2, IIS7.5 均安装有Appfabric for Windows Server