php site not showing any errors but not displaying anything

i know very little php and have set up a copy of a site (db, sitefiles) in iis that has php installed. run the phpinfo.php page so i know php is running and working. when i go to the homepage index.php i j开发者_高级运维ust get a blank page, no errors!!!

any idea how i get to view errors or why this is happening?

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 error_reporting(E_ALL);
 ini_set("display_errors", 1);