Is there any reason why this form would not submit?

I have a form which for some reason does not submit. Is there any particular reason why it would not submit? Here it is:

<div id="formContainer">
<div id="formErrors"></div>
<form id="centeredForm" action="?" method="post">
<p id="formTitle">Register</p>
<table id="formTable">
<tr class="rowHover"><td class="hoverPad">
<label>Username</label>
</td><td>
<input type="text" class="formInput" name="username">
</td></tr>
<tr class="rowHover"><td class="hoverPad">
<label>Email</label>
</td><td>
<input type="text" class="formInput" name="email">
</td></tr>
<tr class="rowHover"><td class="hoverPad">
<label>Password</label>
</td><td>
<input type="password" class="formInput" name="password1">
</td></tr>
<tr class="rowHover"><td class="hoverPad">
<label>Retype Password</label>
</td><td>
<input type="password" class="formInput" name="password2"开发者_开发百科>
</td></tr>
<tr class="rowHover"><td class="hoverPad">
<label>Alpha Code</label>
</td><td>
<input type="text" class="formInput" name="alphacode">
</td></tr>
<tr><td>
</td><td>
<input type="hidden" value="TRUE" name="submitted">
</td></tr>
<tr><td>
</td><td class="rowHover" id="tosRow">
<input id="tosagreeCheck" type="checkbox" name="tosagree">
<label for="tosagreeCheck">I agree to the <a>Terms of Service</a></label>
</td>
</tr><tr>
<td></td>
<td>
<input type="button" value="Sign Up" class="formBttn" name="submit">
</td></tr>
</table>
</form>
</div>

Change

<input type="button" value="Sign Up" class="formBttn" name="submit">

to

<input type="submit" value="Sign Up" class="formBttn" name="submit">