RevitLookup Visual c# express

[Michael Coviello]

I'm trying to use RevitLookup but am having difficulty.
I'm using Visual C# 2010 Express and can successfully build the dll.
I modify the revitlookup.addin file to include the proper path to the dll and copy the revitlookup.addin file to the proper location.
C:\Documents and Settings\All Users\Application Data\Autodesk\REVIT\Addins\2011

Revit Lookup doesn't appear on my addins tab. I'm wondering if theres a limitation to using the express edition and how it creates the addin file.
Any help/direction would be greatly appreciated.


Update:
I had .net 4.0 installed and built the solution with 4.0
When I switched it to 3.5 it worked and loaded!
The target Framework is defined under Project|RevitLookup Properties.