title: ConfigurationManager.AppSettings["KeyName"] not returning any value
body: <p>In my <code>app.config</code> I have added a key with value </p>
  
  <pre><code>&lt;add key="KeyName" value="someValue" /&gt;
  </code></pre>
  
  <p>But in my windows form when i try to access it by using configurationmanager it is not returning anything</p>
  
  <pre><code>ConfigurationManager.AppSettings["KeyName"]
  </code></pre>
  
  <p>this has null value
  Also i dont have any web.config or connection string added in the app.config, but my 
  <code>ConfigurationManager.connectionString</code> returns some value !!</p>
  
  <p>What might be the issue? what should i change?</p>
  
  <p>P.S
  I have added reference to <code>system.configuration</code> and added it in namespace too
  its an excel add-in and has only one class library which has app.config</p>