title: System.Windows.Forms.DataVisualization Namespace Fine in One Class but Not in Another
body: <p>I'm getting this error</p>
  
  <p><code>The type or namespace name 'DataVisualization' does not exist in the namespace 'System.Windows.Forms' (are you missing an assembly reference?)</code></p>
  
  <p>Here is my <code>using</code> section of the class:</p>
  
  <pre><code>using System;
  using System.Collections;
  using System.Collections.Generic;
  using System.Windows.Forms.DataVisualization.Charting;
  using System.Windows.Forms.DataVisualization.Charting.Borders3D;
  using System.Windows.Forms.DataVisualization.Charting.ChartTypes;
  using System.Windows.Forms.DataVisualization.Charting.Data;
  using System.Windows.Forms.DataVisualization.Charting.Formulas;
  using System.Windows.Forms.DataVisualization.Charting.Utilities;
  
  namespace myNamespace {
      public class myClass {
          // Usual class stuff
      }
  }
  </code></pre>
  
  <p>The thing is that I am using the same DataVisualization includes in another class. The only thing that I can think that is different is that the classes that are giving this missing namespace error are Solution Items rather than specific to a project. The projects reference them by link. Anyone have thoughts on what the problem is? I've installed the chart component, .Net 3.5 SP1, and the Chart Add-in for Visual Studio 2008.</p>
  
  <p>UPDATE: I moved the items from Solution Items to be regular members of my project and I'm still seeing the same behavior.</p>
  
  <p>UPDATE 2: Removing the items from the Solution Items and placing them under my project worked. Another project was still referencing the files which is why I didn't think it worked previously. I'm still curious, though, why I couldn't use the namespace when the classes were Solution Items but moving them underneath a project (with no modifications, mind you) instantly made them recognizable. :\</p>