[jQuery] livequery $(this) is null? (this is second post, accidentally clicked post)

[jQuery] livequery $(this) is null? (this is second post, accidentally clicked post)


jQuery.create_table.prepare_add_item=function()
{
    var items=$('#canvas > thead > tr > th');
    var prev_value='';
    var input_item=$('#input_item');
    var head=$('#canvas > thead > tr');
// FIRST METHOD
    $('#canvas > thead > tr > th').click(
        function()
        {
            alert($(this).attr('id'));
        }
    );
///SECOND METHOD
    $('#canvas > thead > tr > th').livequery(
            function()
            {
                $(this).click(function(){
                    alert($(this).attr('id'));
                })
            }
    );
    //THIRD METHOD
    $('#canvas > thead > tr > th').livequery('click',
        function(event)
        {
            var elem=$(this);
            alert(elem.attr('class'));
            if (elem.is('.manipulated'))return;
            elem.addClass('manipulated');//add class that it is being
manipulated
            prev_value=elem.html();//store whatever it's in here before
        //    alert(elem.id);
            elem.empty();
            elem.append(input_item);
        }
    );
THIS IS THE HTML
<table id="canvas" border="1">
    <thead>
        <tr>
            <th id="1">was</th>
            <th id ="2" class="add_item">First item to compare</th>
        </tr>
    </thead>
    <tbody>
        <tr class="add_attr">
            <td> <input type="text" value="" disabled="true"></td>
        </tr>
    </tbody>
</table>
</div>
<span id="assets" style="display:none;">
    <input id="input_item" type="text" />
    <span id="attribute">
        <input id="name" type="text" />
        <select>
            <option>text</option>
            <option>number</option>
            <option>time</option>
            <option>true/false</option>
            <option>video</option>
        </select>
    </span>
</span>
on clicking:
The first method works as advertised.
the second method gives me undefined
the third method gives me undefined and will throw an error on
elem.addClass() , the error is "t has no properties"
Am I missing something?