Add path file page/template
<block type="core/template" name="footerblock" template="page/template/footerblock.phtml" >
<block type="core/template" name="copyright" template="page/template/copyright.phtml" />
or
u can direct access on file:
getLayout()->createBlock('core/template')->setTemplate('page/html/footerblock.phtml')->toHtml();