Select dynamically appended element

Select dynamically appended element

I have a list to which I am creating list items for on the fly in my JQuery script. The problem is, after attaching these elements to the list on the fly I cannot select them. The setup is below, line three never ever works

             var li = "<li>List Item 1</li>";
             $("#mylist").append(li);
            $("#mylist li:first-child").addClass("bold");

Any idea whats going on here? Thanks.