帮忙瞧瞧 验证码对不上 总是输入错误

/* 检查验证码 */
function reg_checkCode(obj)
{
var code = obj.val();
var index = getTabIndex($("#account_content"));
check = obj.next(classname);
if(code==""){
check.html(no+"请输入验证码");
}else if(!check_code(code)){
check.html(no+"验证码输入错误");
updateseccode($("#img_code_"+index));
}else{
check.html(ok);
return true;
}
return false;
}

/* 检查验证码 */
function check_code (code){
return ajax('checkCode',code);
}


//ajax 封装
function ajax (act,cot){
var stat;
jQuery.ajax({
url: "ajax.php",
type:"post",
async:false,
data: {act:act, cot:cot},
success: function(rs){
stat = rs;
}
});
return stat=='1' ? true : false;
}





ajax.php 
<?php
$objUser=new userModel();
$objCookie = new Cookie;
$cookievalidate = $objCookie -> cookievalidate;
$act=$this->spArgs('act');
$cot=$this->spArgs('cot');
switch($act)
{
case 'checkCode':
if(strtoupper($cot) != strtoupper($cookievalidate))
echo 0;
else
echo 1;
break;
default:
echo 'error';

}

?>

php???

CSS code

验证码保存在session中，用session值和当前输入者判断即可