PHP致命错误：无法创建COM对象：服务器执行失败

I am using PHP to create a COM object to read and write to an excel file but when I run this script it gives me this error:

Uncaught exception 'com_exception' with message 'Failed to create COM object 'excel.application':Access is denied.

Then I followed these instructions and now I'm getting the following error message:

PHP Fatal Error: Uncaught exception 'com_exception' with message 'Failed to create COM object `excel.application':Sever execution failed

<?php
 $excel = new COM("excel.application") or die ("Cannot open Excel");
?>

Does any one have an explanation for this error message or solutions?