screwDefaultButtons和php

Question

i added screwDefaultButtons plugin (http://www.screwdefaultbuttons.com) to all my radio buttons and check boxes in all my forms. But i am having some problems in the server side . I am using php and when i am trying to get the post from radio buttons or check-boxes i get undefined index (other input types are working perfectly such as text inputs) .. can anyone help me please ? Below is my screwDefaultButtons code :

$('input:radio').screwDefaultButtons({
     image: 'url("images/radiobuttons.gif")',
        width: 18,
        height: 18
    });
    $('input:checkbox').screwDefaultButtons({
        image: 'url("images/checkboxes.gif")',
      width: 16,
       height: 16
    });

Here's my html code

    <form id="profile-form" METHOD="POST" >
            <tr>
        <td class="formLabelText">Gender</td>
        <td><div class="radioButtonCont">
        <div

 class="selectItemList"><input required type="radio" name="sex" id="male" value="male" checked/> Male</div>
    <div class="selectItemList"><input type="radio" name="sex" id="female" value="female"/> Female</div></div></td>
                                                </tr>

and my php :

if (isset($_POST['sex'])) {
        $sex = mysqli_real_escape_string($connection, trim($_POST['sex']));
    } else {
        $sex = null;
    }

thanks