Why doesn't this work in IE

Hi, the following code is a close button that i have placed on my php page:

echo "<center><input type='button' value='Close' onClick='javascript:window.close();' /></center>";

PHP:

The button works fine in FF but when i click on it in IE it does not do anything

Does anyone know why? Thanks in advance

 

<center> tags are deprecated.

And remove the javascript:


And... it's not a PHP question.