title: Unresolved external symbol _IID / _CLSID
body: <p>I created a default ATL project with MSVC 2010 with a simple default ATL dialog. Then I added the second project into solution, named MyControls, where I created ATL DHTML Control with a help of Wizard. Then I placed ATL DHTML Control to ATL dialog.</p>
  
  <p>Now I would like to call some methods of that ATL DHTML Control in ATL dialog's <code>OnInitDialog</code> function. In order to be able to make a call like:</p>
  
  <pre><code>CComPtr&lt;IDHTMLControl&gt; ptr;
  HRESULT hr = GetDlgControl(IDC_ACTIVEX_CONTROL_DHTML
      , IID_IDHTMLControl, (void**)&amp;ptr);
  </code></pre>
  
  <p>I am including the file DHTMLControl.h from MyControls project. However, I get the following errors:</p>
  
  <ul>
  <li>Error    1   error LNK2001: unresolved external symbol _IID_IDHTMLControl</li>
  <li>Error    2   error LNK2001: unresolved external symbol _LIBID_MyControlsLib</li>
  <li>Error    3   error LNK2001: unresolved external symbol _CLSID_DHTMLControl</li>
  <li>Error    4   error LNK2001: unresolved external symbol _IID_IDHTMLControlUI</li>
  </ul>
  
  <p>Note: It appears that I am linking MyControls.lib incorrectly, however, I added MyControls.lib to Linker->Input->Additonal Dependencies &amp; specified ../$(Configuration) in the Linker->General->Additional Library Directories.</p>
  
  <p>Anyone have an idea?
  Thanks!</p>