[jQuery] next closet or what

[jQuery] next closet or what


I am trying to get the next function working
this works
<table >
<form method="post" id="frmOne">
    <tr>
        <th>Name</th>
        <th>Location</th>
    </tr>
    <tr id="3">
        <td id="2"><input type="checkbox" class="checkbox" name="ss"
value="1"> Spiraldev
        <input type="checkbox" id="rr" class="checkbox" name="ss"
value="1"> Sac Town</td>
    </tr>
</form>
</table>
<script>
$(document).ready(
    function(){
        $( "input.checkbox" ).click(
            function(){
                if($(this).attr('checked') == true){
                    var el = $(this).next();
                    alert($(this).next().attr('id'))
                    $(this).next('[type=checkbox]]').attr('checked',true)
                }else{
                    $(this).next('[type=checkbox]]').attr('checked',false)
                }
            }
        );
    }
);
</script>
but this does not work
<table >
<form method="post" id="frmOne">
    <tr>
        <th>Name</th>
        <th>Location</th>
    </tr>
    <tr id="3">
        <td id="2"><input type="checkbox" class="checkbox" name="ss"
value="1"> Spiraldev</td>
        <td><input type="checkbox" id="rr" class="checkbox" name="ss"
value="1"> Sac Town</td>
    </tr>
</form>
</table>
<script>
$(document).ready(
    function(){
        $( "input.checkbox" ).click(
            function(){
                if($(this).attr('checked') == true){
                    var el = $(this).next();
                    alert($(this).next().attr('id'))
                    $(this).next('[type=checkbox]]').attr('checked',true)
                }else{
                    $(this).next('[type=checkbox]]').attr('checked',false)
                }
            }
        );
    }
);
</script>