Dialog.modal not working Mozilla and IE 6.0

Dialog.modal not working Mozilla and IE 6.0

Hello Guys,
Following is the code I am running
<span style="background-color: rgb(255, 255, 102);">$('#ruleBox').dialog({</span><br style="background-color: rgb(255, 255, 102);"><span style="background-color: rgb(255, 255, 102);">                title:'Exceptions',</span><br style="background-color: rgb(255, 255, 102);">
<span style="background-color: rgb(255, 255, 102);">          <span style="background-color: rgb(255, 204, 255);"></span>      modal:true,</span><br style="background-color: rgb(255, 255, 102);"><span style="background-color: rgb(255, 255, 102);">                position: 'center',</span><br style="background-color: rgb(255, 255, 102);">
<span style="background-color: rgb(255, 255, 102);">                buttons:{</span><br style="background-color: rgb(255, 255, 102);"><span style="background-color: rgb(255, 255, 102);">                    "OK": function(){</span><br style="background-color: rgb(255, 255, 102);">
<span style="background-color: rgb(255, 255, 102);">                        $(this).dialog('close');</span><br style="background-color: rgb(255, 255, 102);"><span style="background-color: rgb(255, 255, 102);">                    }</span><br style="background-color: rgb(255, 255, 102);">
<span style="background-color: rgb(255, 255, 102);">                },</span><br style="background-color: rgb(255, 255, 102);"><span style="background-color: rgb(255, 255, 102);">                close: function(e, ui){</span><br style="background-color: rgb(255, 255, 102);">
<span style="background-color: rgb(255, 255, 102);">                }</span><br style="background-color: rgb(255, 255, 102);"><span style="background-color: rgb(255, 255, 102);">            });</span><br style="background-color: rgb(255, 255, 102);">
But "modal" attribute is not  working properly in Mozilla as well as IE 6.0
Please help me.