问prism.unity中AOP开发时读取配置文件为空？

我的项目结构是这样的。

配置文件是下面

<configuration>

<configSections>

<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Unity.Configuration"/>

</configSections>

<unity>

<typeAliases>

<typeAlias alias="singleton" type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager, Microsoft.Practices.Unity"/>

</typeAliases>

<sectionExtension type="Microsoft.Practices.Unity.InterceptionExtension.Configuration.InterceptionConfigurationExtension, Unity.Interception.Configuration"/>

<containers>

<container name="aopContainer">

<extension type="Interception"/>

<register type="TestUnityAop.BLL.IMenuBll,TestUnityAop" mapTo="TestUnityAop.BLL.MenuBll,TestUnityAop">

<interceptor type="InterfaceInterceptor"/>

<interceptionBehavior type="TestUnityAop.LogBeforeBehavior, TestUnityAop"/>

</register>

<register type="TestUnityAop.ViewModels.MainWinViewModel,TestUnityAop">

<interceptor type="VirtualMethodInterceptor"/>

<interceptionBehavior type="TestUnityAopLogBeforeBehavior, TestUnityAop"/>

</register>

<!--Mash-->

</container>

</containers>

</unity>

</configuration>

App.xaml.cs中的代码是下面

public partial class App : PrismApplication

{

protected override Window CreateShell()

{

/// 使用的容器：Unity

IUnityContainer unityContainer = Container.Resolve<IUnityContainer>();

// 配置文件

ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();

fileMap.ExeConfigFilename = Path.Combine(AppDomain.CurrentDomain.BaseDirectory + "UnityConfig\\Unity.Config");

Configuration configuration = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);

//UnityConfigurationSection configSection = (UnityConfigurationSection)configuration.GetSection(UnityConfigurationSection.SectionName);

UnityConfigurationSection configSection = (UnityConfigurationSection)configuration.GetSection("unity");

configSection.Configure(unityContainer, "aopContainer");

unityContainer.Resolve<IMenuBll>().GetMenus();

return Container.Resolve<MainWin>();

}

}

但运行后报错

就是这个configSection返回值是空，不知是什么原因。望大神帮助一下啊！