Jquery dialog shrinks when i open second time

Hi,

I have a JQuery UI dialog popup that displays data. Popup opens first time perfectly, but second time its not display correctly, dialog shrinks when i open second time. below is my code.

$('#dialogHistory').dialog({

autoOpen: false,

width: 800,

height: 600,

resizable: false,

title: 'History',

resizable: false,

modal: true,

open: function (event, ui) {

$(this).load("@Url.Action("_History", new { id = Model.customer_id })");

});

$("#lnkHistory").click(function () {

$("#dialogHistory").dialog().dialog('open');

});

Thank you,