title: Clickonce Office add-in assembly reference problem upon deployment
body: <p>I have developed an Office 2007 C# add-in. It uses clickonce for deployment. On systems with Office 2010 all is ok but on a machine with XP SP3, NET 3.5sp1 and Office 2007, I get a strange assembly loading error.</p>
  
  <p>My add-in does not directly reference <code>Microsoft.Office.Interop.SmartTag.dll</code>. This gets referenced by <code>Microsoft.Office.Tools.Commmon.v9.0.dll</code> - which IS referenced in my add-in.</p>
  
  <p>When add-in is installed with clickonce an error is reported that the <code>Microsoft.Office.Interop.SmartTag.dll</code> could not be found in my add-in's local install folder. Both <code>Microsoft.Office.Tools.Commmon.v9.0.dll</code> and <code>Microsoft.Office.Interop.SmartTag.dll</code> are in the GAC with correct versions.</p>
  
  <p>I have used <code>Reflector</code> to try and detect the problem but it resolves <code>Microsoft.Office.Interop.SmartTag.dll</code> reference easily by finding the DLL in the GAC.</p>
  
  <p>What are the possible reasons for my clickonce install to fail? The required assemblies are present but GAC is obviously not consulted.</p>
  
  <p>I have found that adding <code>|vstolocal</code> to Manifest registry value makes everything work as expected but still I am wondering why was I getting the error in the first place.</p>