created asp mvc project with framework 4.0 changed to 3.5 and now get errors

I created a small mvc site using framwork 4.0.  I found my hosting company uses 3.5.  I changed my project and compiled and there were no errors.  Now when I run, I get this error on all pages:

 Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0246: The type or namespace name 'dynamic' could not be found (are you missing a using directive or an assembly reference?)

Source Error:

Line 134:    
Line 135:    [System.Runtime.CompilerServices.CompilerGlobalScopeAttribute()]
Line 136:    public class views_page_home_aspx : System.Web.Mvc.ViewPage<dynamic>, System.Web.SessionState.IRequiresSessionState, System.Web.IHttpHandler {
Line 137:        
Line 138:        private static bool @__initialized;

Source File: c:\Users\user1\AppData\Local\Temp\Temporary ASP.NET Files\root\b4d3bd5e\2b9dd07c\App_Web_home.aspx.78bb4944.oap7wvh_.0.cs    Line: 136