I've got a pagetype called Map.php and it uses the default Page.ss Template and an adjusted Layout.

Now I made a copy of Map.php (Map_FB.php which extends Map.php) and made a Map_FB.ss in my templates folder.
That way I can remove the header and footer and put that Map into an iFrame on Facebook.

But the page I created in the CMS still uses the default Page.ss template, not the Map-FB.ss template file.
I flushed the cash, deleted the file and recreated it. But with ?showtemplate=1 it shows me SS uses the page.ss file.

I haven't tried, but the problem is probably be the underscore _

Try renaming your the class in your php file to MapFB and your template MapFB.ss

Templates with _ in the name relate to the page type, then an action on the class - PageType_PageAction.ss.

Hi and thanks for your reply. Think I missed the email notification for this.

I am now using the renderwith function and that works. But I'll try to remove the underscore and see if that works.
I wasn't aware of that. Couldn't find it the docs. Do you have a link for me?