ERROR; global.asax(1) error asp parse could not load type - aspnet_compiler v4.0.30319 used to compile

Hi i am using Visual Web developer 2010, to compile a Csharp web application
targeting Net.framework 4.0,  my OS XP SP3 (IIS 5.1)
 
When I comiple (aspnet_compiler v4.0.30319) i am getting the following error message
global.asax(1) error asp parse could not load type
 
The project was originally developed in Web developer 2008(where It compiled correctly) and later upgraded
 
any idea
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