Dear Bala:
Glad to receive your reply.
The attachment is my project. It is created by VS2008 SP1, the target platform is Net2.0. The steps as followings:
1.Create a WinForm project. VS has automaticly added a subclass of System.Windows.Forms.Form named form1.
2.Modify the form1's fatherclass to RibbonForm class. Build and find no errors.
3.Add some other controls, such as RibbonControlAdv, DockingManager, ToolStripTabItem, TreeViewAdv and so on.Build and find no errors.
4.Delete some controls. Do some necessary modifies and build.
5.Add NavigationBar control onto form and will receive the Exception.
Also I found some other strange issues. When I already added a GroupBar Control and set the properties. Then i build the project, i will receive an Design Error, the message is like "未找到组件所提供的根", in English is like "unable to find the root of the control". Click "ignorn and continue" button, the form opened in design mode, but the groupbar has gone! And then I cannot add groupbar to the form, it will receive the same invalidCastException.
Thank you.
ClientOutlook_7fa9e1da.rar