.net routing same page navigation

im using the asp.net 4 routing mechanism for webforms

now i have a page that opens with a route like this http://localhost:51273/MyApp/Admin/Users/90

on this page i put a hyperlink like this

<asp:HyperLink ID="HyperLink9" runat="server" Text="Items" NavigateUrl="#trItems" />

this should become http://localhost:51273/MyApp/Admin/Users/90/#trItems

but actually becomes http://localhost:51273/MyApp/Admin/#trItems

i dont know if its important, but i also have a physical folder in my webs开发者_开发百科ite called admin. maybe its for some reason referring to that? but i do have in my route register code the following line

RouteTable.Routes.RouteExistingFiles = True

how can this be fixed?

thank you very much

p.s. before i started using routing, these links worked ok.

EDIT

the register code looks like this

RouteTable.Routes.MapPageRoute("Users", "Admin/Users", "~/Admin/Users.aspx", True, Nothing, Nothing, dts)