form submission with Javascript

[Nibinaear]

For some reason this just doesn't work for me. If I click my button which launches this nothing happens.

function submitForm()
{
  document.markForm.submit();
}

<form method="post" name="markForm" id="markForm" action="update_entry.php">

<input type="button" name="submit" value="Update Marks" class="SubmitButton" onClick="submitForm()" />

I can't see anything wrong with that. My button takes the place of my submit as you can see.

Edited:
Eventually found out that I was getting this error in Firefox error console and looked it up:

"Error: document.markForm.submit is not a function"

What I found out is the the submit button with the name of "submit" can clash with the submit function. I changed the submit button's name and it worked fine.