SEVERE: Servlet.service() for servlet [RooSample] in context with path [/RooSample] threw exception [Request processing failed; nested exception is org.apache.tiles.impl.CannotRenderException: ServletException including path '/WEB-INF/layouts/default.jspx'.] with root cause org.apache.jasper.JasperException: /WEB-INF/views/index.jspx (line: 41, column: 109) The prefix "page" for element "page:show" is not bound.

This error is due to the invoking of some Tag-Elements. If you are invoking a particular Tag_Elements in your page, you must mention corresponding "xmlns" or "prefix" at the top of page.

Here you have to mention the the prefix "page" before you are invoking element "page:show"

Code:
index.jspx
-------------

<div xmlns:field="urn:jsptagdir:/WEB-INF/tags/form/fields" xmlns:jsp="http://java.sun.com/JSP/Page" xmlns:page="urn:jsptagdir:/WEB-INF/tags/form" version="2.0">
   
    <page:show id="ps_com_assyst_Timer" object="${timer}" path="/timers"                     z="dcIHCOvJZSL/kCAw2V/VQSftNhk=">
        <field:display field="message" id="s_com_assyst_Timer_message" object="${timer}" z="230qJe8e+RzBrzzlHoulj/KSIH8="/>
    </page:show>
</div>