After I've added a single page into the dashboard single pages list it won't display the php when I surf to the link or click the href on my page.

Even when I take an existing single page and copy it to another name and the include it into the dashboard this page won't work an give some error like :

Warning: include(/opt/lampp/htdocs/concrete5.6.1.2/concrete/single_pages/contentAjaxPage.php): failed to open stream: No such file or directory in /opt/lampp/htdocs/concrete5.6.1.2/concrete/core/libraries/view.php on line 905

Warning: include(): Failed opening '/opt/lampp/htdocs/concrete5.6.1.2/concrete/single_pages/contentAjaxPage.php' for inclusion (include_path='/opt/lampp/htdocs/concrete5.6.1.2/libraries/3rdparty:/opt/lampp/htdocs/concrete5.6.1.2/concrete/libraries/3rdparty:.:/opt/lampp/lib/php') in /opt/lampp/htdocs/concrete5.6.1.2/concrete/core/libraries/view.php on line 905


I've checked unix permissions and those seem legit and concrete should be able to access the file