extending visual studio project property grid

Question

hi, I'm trying to extend project property grid, using dte in following way applicationObject.ObjectExtenders.RegisterExtenderProvider(Constants.vsCATIDMiscFilesProject,"A",new TestExtenderProvider(),"a"); applicationObject.ObjectExtenders.RegisterExtenderProvider(Constants.vsCATIDGenericProject,"A",new TestExtenderProvider(),"a"); applicationObject.ObjectExtenders.RegisterExtenderProvider(Constants.vsCATIDSolutionBrowseObject,"A",new TestExtenderProvider(),"a"); applicationObject.ObjectExtenders.RegisterExtenderProvider(Constants.vsCATIDMiscFilesProjectItem,"A",new TestExtenderProvider(),"a"); applicationObject.ObjectExtenders.RegisterExtenderProvider(Constants.vsCATIDDocument,"A",new TestExtenderProvider(),"a"); applicationObject.ObjectExtenders.RegisterExtenderProvider(Constants.vsCATIDSolution,"A",new TestExtenderProvider(),"a"); where TestExtenderProvider is some provider that returns a class with one constant property but for some reason it works only for solution property grid,although I defined it for all kinds of files(CanExtend in extend provider always returns true). is there some mistake?