RouteCollection.ignore doesn't work

Question

I use RouteCollection with FriendlyUrlSettings to remove aspx from being shown... so now every time someone access my site, instead of display www.mysite.com/login.aspx , it will display www.mysite.com/login
But I have a problem where an old app needs to access a page, and it's already hard-coded inside the app to access www.mysite.com/service/AuthenticateUser.aspx page. But because of the friendlyurl, the app doesn't work.
So I added this line
routes.Ignore("Service/AuthenticateUser.aspx");but it doesn't seem to do anything. Every time I access the page Service/AuthenticateUser.aspx , it will still redirect me to Service/AuthenticateUser only