Small Javascript Question

Hi,

I have a form which puts out a hidden DIV like this:


<DIV id='invalid' style="display:none"><img src="../images/
flyer.jpg"></DIV>

So, the DIV is hidden until the customer performs some actions.  Once
they do, I make the DIV appear like this:

do***ent.getElementsByName('custphoto')[0].style.display="";

That works fine in IE.  But Firefox gives this error:

Error: do***ent.getElementsByName("custphoto")[0] has no properties

Why does that not work in Firefox, but does in IE?   Can I make it
work in both browsers???

Thank you!