Javascript question - works in FF, but not in IE

Hello, new subscriber here...I'm trying to fix some javascript. It works as expected in Firefox, but not in Internet Explorer. FWIW, am using FF 3.0.14 and IE 7.0.6.

The code is up on pastebin here: http://pastebin.com/m20949cd1 

I'm aware that setAttribute & getAttribute are buggy in Internet Explorer, so (in an alternate version of the code) I replaced the toggle bit in function createToggleFunction with the following:

	
if (toggleElement.className == 'collapsibleClosed') {
		toggleElement.className = 'collapsibleOpen';
		toggleElement.src = OPEN_IMAGE;
	} else {
		toggleElement.className = 'collapsibleClosed';
                                toggleElement.src = CLOSED_IMAGE; 
	}


However, I must assume I did something wrong in the code above, because it doesn't work in Firefox. 

Any thoughts? Let me know if I need to provide more information.

Thanks,

Laura Harris
Web Services Librarian
Grand Valley State University
Allendale, MI 49401