c# Appsettings giving error: The name 'ConfigurationManager' does not exist in the current context
<p>At the top of my program I have the following:</p>

<pre><code>       using System.Configuration;
</code></pre>

<p>Within my code, I have the following:</p>

<pre><code>    int  CompanyID = Convert.ToInt32(ConfigurationManager.AppSettings["CompanyId"].ToString());
</code></pre>

<p>I am getting the following error though: </p>

<p><strong>The name 'ConfigurationManager' does not exist in the current context</strong></p>

<p>I am not sure what I am missing.     </p>
