Compilation Error

Server Error in '/' Application.

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: CS0234: The type or namespace name 'TreeNode' does not exist in the namespace 'CMS.TreeEngine' (are you missing an assembly reference?)

Source Error:

Line 10: using CMS.PortalEngine;
Line 11: 
Line 12: using TreeNode = CMS.TreeEngine.TreeNode;
Line 13: 
Line 14: public partial class CMSWebParts_Blogs_SCRecentPosts: CMSAbstractWebPart

Source File: e:\Web\CMS_7\CMSWebParts\Blogs\SCRecentPosts.ascx.cs    Line: 12

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1016