为什么我的这段代码，点击注册后，没有执行checkall()

<script language="javascript" type="text/javascript">此处省略一些代码function checkall()
{
checkUsername($('#username').val());
checkpass($('#password').val());
checkpass2();
checkqq2(document.getElementById('qq2').value);
checkemail();
checkyzm();
if(ddName==0||ddPass==0||ddPass2==0||ddYzm==0||ddQq==0)
{
alert('请填写完注册内容！');
return false;
}
else
{
return true;
}
}
</script>
</head><body>
<form id="form" name="form" method="post" action="savereg.php" onsubmit="return checkall()">
<input type="hidden" value="<?php echo $grec?>" name="rec" id="rec" />
<div id="maincenter">
<div id="maincenterleft">
  <div style=" margin-bottom:20px; margin-left:20px;"><img src="../template/<?php echo MOBAN ?>/images/logo.gif" /></div>
  <table width="480" border="0" align="left" cellpadding="0" cellspacing="0" bordercolorlight="#9acd32" hight="100" name="zhuce" style="font-size:14px;">
<tr>
  <td width="18%" height="35" align="right" class="altbg1 STYLE2">&nbsp;&nbsp;用户名 *&nbsp;&nbsp;</td>
  <td height="35" colspan="2"><span class="STYLE2">
    <input name="username" type="text" onblur="checkUsername(document.getElementById('username').value);" onkeyup="value=value.replace(/[^\d]/g,'') " onbeforepaste="clipboardData.setData('text',clipboardData.getData('text').replace(/[^\d]/g,''))" size="20" maxlength="20" style="width:130px;" id="username" class="ddinput" />
  </span></td>
  <td width="51%" height="35" id="ckuser">用户名（5-12位数字</td>
</tr>
<tr>
  <td height="35" align="right" class="altbg1 STYLE2">密&nbsp;&nbsp;&nbsp;&nbsp;码 *&nbsp;&nbsp;</td>
  <td height="35" colspan="2"><span class="STYLE2">
    <input name="password" type="password" id="password"  onblur="checkpass(document.getElementById('password').value);" size="20" maxlength="20" style="width:130px;" class="ddinput"/>
  </span></td>
  <td width="51%" height="35" id="ckpass">密码为长度 3 - 20 位</td>
</tr>
<tr>
  <td height="35" align="right" class="altbg1 STYLE2">确认密码 *&nbsp;&nbsp;</td>
  <td height="35" colspan="2"><span class="STYLE2">
    <input name="password2" type="password" id="password_check" onblur="checkpass2();"  size="20" maxlength="20" style="width:130px;" class="ddinput"/>
  </span></td>
  <td width="51%" height="35" id="ckpass2">请再次确认密码</td>
</tr>
<tr>
  <td height="35" align="right" class="altbg1 STYLE2">验 证 码 *&nbsp;&nbsp;</td>
  <td height="35" colspan="2"><span class="STYLE2">
    <input name="yzm" type="text" id="yzm" onblur="checkyzm();"  size="6" maxlength="4" style="width:50px;" class="ddinput"/>
  </span>&nbsp;&nbsp;<img style="cursor:pointer" src="../comm/yzm.php" border="0" align="absmiddle" onclick="this.src='../comm/yzm.php?a='+Math.random()"/></td>
  <td width="51%" height="35" id="ckyzm">请填写验证码</td>
</tr>
<tr>
  <td height="35" align="right" class="altbg1">&nbsp;</td>
  <td height="35" colspan="2"><input type="submit" name="Submit" value="马上注册" class="ddbutton" /></td>
  <td width="51%" height="35"></td>
</tr>
  </table>
</div>
<div id="maincenterright" style="line-height:25px;">