PHP Errors are not showing up in the browser

I am facing a strange problem. I have set up everything in php.ini file. But i can't get any errors showing up in the browser. I googled to set up the .ini file and did all the required things. But still i am not able to get error message displaying in the browser. My PHP ini settings,

display_errors = On
display_startup_errors = On
error_reporting = E_ALL | E_STRICT
log_errors = On
track_errors = On

I tried with the following code to see error message,

<?php
      require_once("sample.php");
 ?>

Actually the file sample is not available. So it must show Fatal error. But it is showing a blank page.

Can you point me out to fix this? I don't know what i am missing here.

Solution

I found the problem. Actually, PHP is installed with XDebug extension. So the problem is in that extension. Even i was not aware of that. Because this system was used by someone previously. I uninstalled and installed again with new supported version. It works now. Thanks and sorry for the inconvenience friends.