Forms Security Problem

[Matt]

Ok, second issue of the day.
I have a site I am trying to protect using forms based security

My main section is public and is configured fo ranonymous access, i.e. in
the web.config file
<authentication mode="Forms"/>
<authorization>
<allow users="*"/>
</authorization>

I then copied my web.conf file to a subfolder, and changed it so that the
appropriate sections read
<authentication mode="Forms">
<forms name="cookiename" loginUrl="Login.aspx"> // File is In the subfolder
</authentication>

<authorization>
<deny users="?"/>
</authorization>

I then get an error on running "could not load type ap1.ap2.Login.aspx

I have checked that all the dlls are in the root / bin folder

I have also checked and using IIS my subfolder is configured to be an
application

A colleague vaguely remembers doing this before and needing to remove some
of the information in the web.config file, but after some trial and error I
am getting nowhere.

Any clues, or any other obvious things to check?