"the jspx document is not a valid page template or content presenter template. Recognizing the resource type as Page Style"
I got this problem when I decided to created my on custom template for my portal application. But it is very simple issue. To resolve it
we need a "content" facet for our template and its reference. So open your template in source view and add
"<facet>
<description>Facet for content</description>
<facet-name>content</facet-name>
...
