Have been trying to post uploaded document alongside other text fields to a php script using jquery's submit function but so far unsuccessful. The text fields are successfully posted. I have no idea what the problem is. PLease assist.
Jquery submit code
    submitHandler: function(form) {
            $.post('bin/insert.php', $("#form").serialize(), 
            function(data) {
              if(data.length > 0 )
              {
                  $('.success_box').fadeIn(800);
                 $('.success_box').html(data);
              }
            });
            }
php script
            if(isset($_POST['save']))
   {
            $upload_dir = "./docs"; 
    $upload_path = $upload_dir."/";
    $userfile_name = $_FILES['image']['name'];
    $userfile_tmp = $_FILES['image']['tmp_name'];
    $userfile_size = $_FILES['image']['size'];
    $filename = basename($_FILES['image']['name']);
    $file_ext = substr($filename, strrpos($filename, '.') + 1);
    $large_image_name  = $filename;
            if($userfile_name==NULL){
    echo "<img src='./warning.png' align='center'>You have not selected a      document to upload";
    exit();
}
}
I get the above error message on posting the form.
 
     
     
    