[php] no error message display

Dear all,

I am writing some PHP script in IIS
I got a problem on error message display … like …

<?php
echo "hello world;
?>

the above script has a missing double quote…
if i test run in a browser, it only comes up with an empty page without error message …

How do I configure the PHP or IIS to show up the error message ??
need to configure teh PHP.INI ???

Thanks
Sam