page.tpl.php no working

Hi.

I am using the html.tpl.php from the default Omega theme on my subtheme and works as is expected (I have copied omega/templates/system/html.tpl.php to subtheme mysubtheme/templates/system/html.tpl.php) and any change made is displayed on the browser, but if is used the page.tpl.php on the subtheme (mysubtheme/templates/system/page.tpl.php), no changes are displayed. I have cleared chaches, and nothing. what could be the cause? this is as expected behavior? I mean, is needed some kind of additional/different step/s to display changes of page.tpl.php on the browser?