jQuery Grid Plugin - jqGrid

First the code look like : "demo New in version 3.4 = >Import Configuration from XML", I change the colModel to be editable.

I want to import the config and data form server side, and  do "add, edit, del" actions. But I find that the navigation can't work, for example, when I click the add button, no  colModel displayed!

$("#cnvxml").click(function(){
    $("#xmlist1").jqGrid('jqGridImport',{
        imptype: 'xml',
        impurl: "testxml.xml",
        'importComplete': function(){
            jQuery("#xmlist1").jqGrid('navGrid', '#xmlpager1', {});
        }
    });    
 
    $(this).hide();
});