Toggling visibility of an object in JS

[Robert64]

I have a .swf that I am trying to hide and show using Javascript. These are my hiding / showing functions:

<script language="JavaScript">
	function hideswf() {
		document.getElementById('swf').display = 'none';
		document.getElementById('mask').display = '';
	}
	function showswf() {
		document.getElementById('swf').display = '';
		document.getElementById('mask').display = 'none';
	}
</script>

The id of the div containing the .swf is definately "swf", and the div containing the link to the function has an id of "mask". The function definately calls because I put an alert in there to test. Why won't it work?
You can see the whole page [url="http://www.robertandsherman.co.uk/view.php?postno=7"]here[/url].

[Dragory]

<script language="JavaScript">
	function hideswf() {
		document.getElementById('swf').style.display = 'none';
		document.getElementById('mask').style.display = '';
	}
	function showswf() {
		document.getElementById('swf').style.display = '';
		document.getElementById('mask').style.display = 'none';
	}
</script>

There you go.

[editline]01:11AM[/editline]

Also, I'm not sure if [I]display = ''[/I] works.

[Robert64]

Thanks, that was quite stupid :/