Logout grayscale function

[teonix]

Hello,

I'm trying to add the logout function to a non-vB page. The prompt part is working, but I cannot seem to get the grayscale part to work.

I am currently adding this code to my non-vB page..

<!--
function log_out()
{
	ht = document.getElementsByTagName("html");
	ht[0].style.filter = "progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)";
	if (confirm('$vbphrase[sure_you_want_to_log_out]'))
	{
		return true;
	}
	else
	{
		ht[0].style.filter = "";
		return false;
	}
}
//-->
</script>

And then utilizing the function in the logout <a href> by adding

onclick="return log_out()"

The javascript prompt pops up, but the page doesn't convert to grayscale like it does on a vB page

Any ideas? Is there something i'm missing that I need to include?