Allow access to a page for all users (including unauthenticated)

I need to allow access to an aspx page to all users (including unauthenticated users)
this page is in folder "Admin" which already has some rules










there are also lines









for allowing access to a page I added following lines









but there is no effect - asp.net still requires authentication to access that page
I tried to comment out 1st part of code - still no effect
I only was able to make it work by removing authentication at all (...)
There are some aspx pages in my site which are accessible for all users - but for some reason the same way doesn?t work for Admin/AccessibleForAll.aspx page

Anyone have ideas what is the problem here and how I can make it work?
...