Unable to cast object of type 'ProfileCommon' to type 'MyApp1.ProfileCommon'.

I converted website to Web Application.
Copy Pasted ProfileCommon.cs from autogenerated class to Hard Codes cs file added to project
Changed  virtual method to static
(public static ProfileCommon GetProfile(string username)) whats the problem here ?
Unable to cast object of type 'ProfileCommon' to type 'MyApp1.ProfileCommon'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidCastException: Unable to cast object of type 'ProfileCommon' to type ' ...