title: ComponentGroupRef not working with WiX library
body: <p>I created a library in WiX with a single ComponentGroup, Component and File, this way:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"&gt;
  &lt;Fragment&gt;
    &lt;ComponentGroup Id="MyComponentGroup" Directory="WindowsFolder"&gt;
      &lt;Component Id="MyComponent" Guid="..."&gt;
        &lt;File Id="MyFile" Source="file.txt" KeyPath="yes" /&gt;
      &lt;/Component&gt;
    &lt;/ComponentGroup&gt;
  &lt;/Fragment&gt;
  &lt;/Wix&gt;
  </code></pre>
  
  <p>Then I created a WiX project, added a reference to this library (as a project reference) and I'm using this code:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"&gt;
  &lt;Product Id="*" Name="My Product" Language="1033"
           Version="1.0.0.0" Manufacturer="Myself"
           UpgradeCode="xxxxx"&gt;
    &lt;Package InstallerVersion="200" Compressed="yes" InstallScope="perMachine" /&gt;
  
    &lt;Feature Id="Feature_Product" Title="Main Product"
           Level="1" Absent="disallow" Description="Core functionality."&gt;
      &lt;ComponentGroupRef Id="MyComponentGroup" /&gt;
    &lt;/Feature&gt;
  &lt;/Product&gt;
  
  &lt;Fragment&gt;
    &lt;Directory Id="TARGETDIR" Name="SourceDir"&gt;
      &lt;Directory Id="WindowsFolder" /&gt;
    &lt;/Directory&gt;
  &lt;/Fragment&gt;
  &lt;/Wix&gt;
  </code></pre>
  
  <p>But I'm receiving an error of <code>Unresolved reference</code>. Is there anything I'm missing? <strike>Or do libraries only work with UI and not files?</strike></p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I added the complete code.</p>
  
  <p>And it works if I use a <code>FeatureRef</code> and I move the <code>Feature</code> to the library, but I would like to keep the Feature in the main project and only have the <code>Component</code> in the library.</p>