I try to create a pdf document you can see the code below. but when I try to open it, it works like an ordinary xhtml page.

<p:document xmlns:p="http://jboss.com/products/seam/pdf"> 
    <p:image alignment="right" wrap="true" resource="/logo.jpg" />
    <p:font size="24">
        <p:paragraph spacingAfter="50">My First Document</p:paragraph>
    </p:font>

    <p:paragraph alignment="justify">
        This is a simple document.  It isn't very fancy.
    </p:paragraph>
</p:document>

Here is my output

My First Document This is a simple document. It isn't very fancy. 

There are no paragraphs, no font size, nothing. Do you have any idea why it works like this?