Submit Form Using Rollover Image

I would like to use a rollover image as a submit button for my form. I am using the <A HREF....> approach as follows:

<a href=javascript:go_submit(document.EnterCTAMembership)><IMG SRC="../../pics/continueoff.gif" WIDTH=83 HEIGHT=34 BORDER=0 ALT="" NAME="continue" onMouseOut="MM_swapImgRestore()" onMouseOver="MM_swapImage('continue','','../../pics/continueon.gif',1)"></A>

However, the form does not submit. All that happens is that the current page reloads. I'm using IE 5.0. How do I get this to submit as a rollover image? I couldn't use INPUT TYPE="IMAGE" because I can't get the rollover to work.

Help!

function subit(){
document.formname.submit()
}

<form name="formname" etc etc
<a href="#" onclick="subit()"><IMG SRC="../../pics/continueoff.gif" WIDT etc etc

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Simon Wheeler
FirePages -DHTML/PHP/MySQL