Problems with AJAX an <location deny users=? ...

[Guest]

I'm having problems executing AJAX request when mi location element is like:

<location>
<system.web>
<httpHandlers>
<add verb="POST,GET" path="*.ashx" type="Ajax.PageHandlerFactory, Ajax" />
</httpHandlers>
<authorization>
<deny users="?"/>
</authorization>
<system.web>
</location>

How can I write a location element to allow all AJAX requets keeping forms
based authentication

Thanks in advance.