html5 form not reacting to submit - php

Question

I've got a simple one-page form, the kind I've written dozens of times, but this behavior is totally new to me. At first, it was submitting on page-load, thus redirecting automatically to the next page in the series. I'm still not sure how I got that to stop, but now it's not doing anything at all when you hit "submit". The page simply sits there.
I've tried stripping out the error-checking scripts, the show/hide script, even jquery itself, then taking the form down to just one input. I tried getting rid of the redirect and just having it output a simple line, then vardump, and still nothing. I hit submit, and no matter what I do, the page just sits there. I've never run into behavior like this before, and firebug et al give me no errors or leads.
If anyone has any ideas at all, no matter how crazy, I'm willing to try. I'm at a loss. Thanks in advance!
<?php
session_start();
include('functions.php');
if ($_POST['submit']) {
$company = $_POST['company'];
$taxid = $_POST['taxid'];
header("location:step2.php");
}
include('head.php'); ?>
<form method="post" name="basic" action="step1.php">
<div class="col70">
<label for="company">Organization/Business name <img src="img/req.jpg" alt="required"></label>
<input type="text" name="company" id="company" value="" />
</div>
<div class="col30">
<label for="taxid">Taxpayer ID# (IEN or SS#) <img src="img/req.jpg" alt="required"></label>
<input type="text" name="taxid" id="taxid" value="" />
</div>
<div class="newcol">
<label for="address">Mailing Address <img src="img/req.jpg" alt="required"></label>
<input type="text" name="address" id="address" value="" />
</div>
<div class="col30 newcol">
<label for="city">City <img src="img/req.jpg" alt="required"></label>
<input type="text" name="city" id="city" value="" />
</div>
<div class="col30">
<label for="state">State <img src="img/req.jpg" alt="required"></label>
<select name="state" id="state" tabindex="<?php echo $tabin; $tabin++; ?>">
<option value="0"></option>
<option value="1">Alabama</option>
</select>
</div>
<div class="col25">
<label for="zipcode">Zip Code <img src="img/req.jpg" alt="required"></label>
<input type="text" name="zipcode" id="zipcode" value="" />
</div>
<fieldset><legend>1. What kind of group/company do you have? <img src="img/req.jpg" alt="required"></legend>
<span id="nfpfp" class="InputGroup">
<label><input name="nfpfp" id="nfpfp_1" type="radio" value="1" />For-profit business.</label>
<label><input name="nfpfp" id="nfpfp_2" type="radio" value="2" />Non-profit 501(c)3 organization.</label>
</span>
</fieldset>
<fieldset><legend>2. How will you use the booth space? Select all that apply. <img src="img/req.jpg" alt="required"></legend>
<span id="type" class="InputGroup">
<label><input name="food" id="type_1" type="checkbox" value="1" />Food sales</label>
<label><input name="retail" id="type_2" type="checkbox" value="2" />Retail sales</label>
<label><input name="activity" id="type_3" type="checkbox" value="3" />Activity</label>
<label><input name="display" id="type_4" type="checkbox" value="4" />Display</label>
<label><input name="other" id="type_5" type="checkbox" value="5" />Other</label>
</span>
</fieldset>
<label for="otherdetails" class="newcol offsides">Enter a short description of your use. (Ex: "BBQ sandwiches", "kite kits", "face painting".) <img src="img/req.jpg" alt="required"></label>
<input type="text" name="otherdetails" id="otherdetails" value="" />
<fieldset><legend>3. Select any/all that apply. Additional questions may appear, if further information is required.</legend>
<span id="additional" class="InputGroup">
<label><input name="raffle" id="raffle_1" type="checkbox" class="switchcheck1" value="1" />I'll be selling raffle tickets and/or holding a raffle at the festival.</label>
<div class="newcol offstate1">
<label for="raffledetails">You'll need written permission from the Exchange Club. Please enter details about the raffle. <img src="img/req.jpg" alt="required"></label>
<textarea name="raffledetails" id="raffledetails" tabindex="<?php echo $tabin; $tabin++; ?>"></textarea>
</div>
<label><input name="trailer" type="checkbox" id="trailer_1" value="1">I'll be bringing a trailer.</label>
<label><input name="outlets" type="checkbox" id="outlets_1" class="switchcheck2" value="1" />I'll require electrical outlets.</label>
<div class="newcol offstate2">
<label for="outletsdetails">How many outlets will you require? <img src="img/req.jpg" alt="required"></label>
<input type="text" name="outletsdetails" id="outletsdetails" />
</div>
</span>
</fieldset>
<input type="button" name="submit" class="a_button" value="submit" />
</form>

Answer 1

The element with name="submit" is of type button and not submit, so it renders a plain button that does nothing (with the intention that you bind some JavaScript to it).
Use type="submit" instead.

Answer 2

Try
<input type="submit" name="submit" class="a_button" value="submit" />
for your submit button.