> set VSTO_SUPPRESSDISPLAYALERTS=0
> C:\Program Files\Microsoft Office\OFFICE11\OUTLOOK.EXE
The familiar debugging box should then pop up telling you why your addin failed. If it doesn't pop up make sure that the value for the registry key at HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\YourAddInName\LoadBehavior = 3