Drag and drop not working while using JQuery UI dialog

Question

Hi Guys !

I m using jquery ui.core.js with version 1.7.2 and jquery-1.4.2.js . I got the issue saying "proto.plugins"(query ui.core.js for draggable module) is undefined ,hence i am not able to perform the drag option.My Code is given below.

$("#linkfortag").click(function(){
            var $dialog=$("<div id='testing'></div>").dialog({autoOpen:false});
            $dialog.dialog("destroy");
            $dialog.draggable();

            alert("$dialog is" + $dialog.html());
            $dialog.dialog('open');
            $dialog.dialog({title:'Add Tag',resizable:true,closeOnEscape:true,modal:true,minWidth:250,buttons:{
                    'Add Tag':function() { alert($(this).children().children().children(':input').attr('value'));
                                            var value=$("#addTag").attr('value');
                                            var formobj=$(this).children();
                                            validate_usertagform(value);
                                            }
                    ,'Cancel': function() {$(this).dialog('close');}}});
                    $dialog.bind("dialogbeforeclose",function(event,ui){
                                    alert("Dialog is gng to close");
alert("<<<<<<<<<<<<<<<<<UI IS>>>>>>>>>>>>>>>>>>>>>>" + ui);
                                            });
                    $dialog.bind("drag",function(event,ui){
                                    alert("<<<<<<<<<<<<<<<<<drag is>>>>>>>>>>>>>" + event);

                                    });

            $dialog.dialog( "option", "closeText", '' );
            $dialog.dialog("option","draggable",true);
            });

Please help me on this........