Be aware that your list is not a real form element so there's nothing there to submit. But that doesn't explain why your script isn't working as expected.
First of all, don't use onclick and similar attributes in the HTML; that's a poor practice. Use unobtrusive JavaScript and keep all script confined to <script> blocks.
You should also use jQuery to make it all much much easier.
First thing I would do is to establish a click handler for the list elements and set a breakpoint (using the browser Dev tools) to see if the handler is being called. From there, you can diagnose the statement that submits the form.
