插入MYSQL数据库使用jquery/ajax 500内部服务器错误

我插入无线电检查数据值mysql数据库与php/jquery和ajax，而插入值我得到内部服务器500错误…

任何帮助都是感激的。

<div>
    <input class="radio_div_clicked" value="<?php echo $row['name'];?> name="radio_section" id="<?php echo $row['id'];?>"/>
    <p><?php echo $row['name'];?></p>
    <button id="add_feed">Add</button>
</div>

JQUERY代码

<script type="text/javascript">
$('body').delegate('#add_feed','click',function(){
    var radio_div_clicked = $('input:radio[name=radio_section]:checked').val();
    $.ajax({
            type:"POST",
            url:"index.php",
            cache: false,
            data:{
                insert_section:1,
                radio_div_clicked:radio_div_clicked
            },
            success:function(data)
            {
                alert('Successfully Inserted Into Table');
            }
        });
    }
});
</script>

<?php 
    $con = @mysql_connect('localhost','root','') or die('failed to connect server');
    $db = mysql_select_db('demo',$con) or die('failed to select db');
    if(isset($_POST['insert_section']))
    {
        $radio_div_clicked = mysql_real_escape_string($_POST['radio_div_clicked']);
        $sql = mysql_query("insert into test(name) values($radio_div_clicked)";
        if($sql)
        {
            echo "Successfully Inserted Into Table";
        }
        else
        {
            echo "Failed To Insert Value Into Table"
        }
    }
?>
<?php 
    mysql_close ($con);
?>