I am having a problem with the <apex:composition> tag. I have created my Sites application in my development org and packaged the VF pages and Controller into a managed package.

When I install the package into the destination org, the only Site Template I'm able to use is the site template that I packaged with my app. I want to allow the user to create their own Site Template (unmanaged, in their org) and set this page as the Site Template.

To be perfectly clear, this is what I'm doing:

<apex:page>
    <apex:composition template="{!$Site.Template}">
        <apex:define name="body">

            Blah blah blah

         </apex:define>
    </apex:composition>
</apex:page>

And the template I package with my app:

 <apex:page >
        <div class="content"><apex:insert name="body" /></div>
        <div class="footer">
            <apex:outputText value="Copyright 2009"/>

         </div>
</apex:page>

When I deploy my package, if i configure my Site to use the template that I've packaged, everything works fine. But the moment I change the Site Template to point at a different template that didn't come with my package, I get a 404/File Not Found