JS not submitting form?

I'm fairly new to JS programming, but I'm wondering if I'm not doing something right... here is my issue:

I have a form that when they select 'continue' the JS is supposed to post back to the same form where some PHP code gets invoked.

Here is a quick snipit:
function nextpage() {
document.train.text2.value = "continue";
document.train.submit();
}
<form action="Episode1_train.php" method="POST" name="train" >


<a href="javascript:nextpage();"><img src="/global/images/xp_save.gif" border="0" />
</a>

is there something that I'm missing? What could I add?