Question : Unrecognized attribute targetFramework error: W2003 & IIS 6

I have an application which I have just moved from .Net 3..5 to 4.0.  Works great on my development machine (Windows 7) but when I deploy to Windows 2003 production server it chokes giving me Unrecognized attribute 'targetFramework' error.

I have installed .Net 4.0 Framework and enabled the set the Web Service Extention to Allowed.  I have set the ASP.Net version to 4 for the application.  

Answer : Unrecognized attribute targetFramework error: W2003 & IIS 6

You might have come across this ..but if not: http://forums.asp.net/t/1491204.aspx
Two things to note:
1: Setting application pool
2: Right framework version on server..