[c#] 구성 요소가 선언되지 않았습니다.

Visual Studio 2012 Express Edition에서 몇 가지 작업을하고 있습니다. 다음과 같이 App.config XML 파일을 추가했습니다.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
</configuration>

가장 먼저 발생하는 것은 ” ‘configuration’요소가 선언되지 않았습니다.”라는 경고가 표시되는 것입니다. 왜 이런 일이 일어나는지 아는 사람이 있습니까? 이 문제가 해결 될 때까지 요소를 내부에서 선언 할 수없는 것 같습니다.

감사!

다음은 전체 XML입니다.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
<appSettings>
<add key="Version" value="779" />
<add key="TimeOut" value="60000" />
<add key="LogFileName" value="Log.txt" />
<!-- your Developer Id with eBay -->
<add key="Environment.DevId" value="" />
<!-- your Application Id with eBay -->
<add key="Environment.AppId" value="" />
<!-- your Application Certificate with eBay -->
<add key="Environment.CertId" value="" />
<!-- API Server URL -->
<!-- For production site use: https://api.ebay.com/wsapi -->
<!-- For Sandbox use: https://api.sandbox.ebay.com/wsapi -->
<add key="Environment.ApiServerUrl" value="https://api.sandbox.ebay.com/wsapi" />
<!-- EPS Server URL -->
<!-- For production site use: https://api.ebay.com/ws/api.dll"/-->
<add key="Environment.EpsServerUrl" value="https://api.sandbox.ebay.com/ws/api.dll" />
<!-- eBay Signin URL -->
<!-- For production site use: https://signin.ebay.com/ws/eBayISAPI.dll?SignIn -->
<!-- https://signin.sandbox.ebay.com/ws/eBayISAPI.dll?SignIn -->
<add key="Environment.SignInUrl" value="https://signin.sandbox.ebay.com/ws/eBayISAPI.dll?SignIn" />
<!-- ViewItem URL -->
<!-- For production site use: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&amp;item={0} -->
<add key="Environment.ViewItemUrl" value="http://cgi.sandbox.ebay.com/ws/eBayISAPI.dll?ViewItem&amp;item={0}" />
<!-- token is for both API server and EPS server -->
<add key="UserAccount.ApiToken" value="" />
<!-- eBay site ID -->
<add key="UserAccount.eBayUserSiteId" value="0" />
<add key="logexception" value="true"/>
<add key="logmessages" value="true"/>
<add key="logsdkmessages" value="true"/>
<add key="logsdk" value="true"/>
<add key="logfile" value="Log.txt"/>
<!-- Rule Name-->
<add key="RuName" value=""/>
<!-- Set this if you access eBay API server behind a proxy server-->
<add key="Proxy.Host" value =""/>
<add key="Proxy.Port" value =""/>
<!-- set proxy server username/password if necessary-->
<add key="Proxy.Username" value=""/>
<add key="Proxy.Password" value=""/>