I must be missing something obvious. But I have an  intermittent problem

with the pager not showing, in the main grid and never in the sub grid. Works fine on my other pages:-

// JavaScript Document
$(document).ready(function(){
$("#editusergrid").jqGrid({
       url:'inc/asp/ajaxGridUserAdd.asp',
    pager: jQuery('#edituserpagergrid'),
    datatype: "xml",
       colNames:['ID', 'UserName', 'FirstName', 'LastName', 'Password', 'Salary', 'Admin?', 'Active?'],
       colModel:[
           {name:'UserID',index:'UserID', width:60,editable:false,editoptions:{readonly:true,size:10}},
           {name:'UserName',index:'UserName', width:100,editable:true,editoptions:{size:25},editrules:{required:true}},
           {name:'FirstName',index:'FirstName', width:100,editable:true,editoptions:{size:25},editrules:{required:true}},
        {name:'LastName',index:'LastName', width:100,editable:true,editoptions:{size:25},editrules:{required:true}},
        {name:'Password',index:'Password', width:100,editable:true,editoptions:{size:25},editrules:{required:true}},
        {name:'Salary',index:'Salary', width:70,editable:true,editoptions:{size:10},editrules:{required:true,number:true}},
        {name:'Admin',index:'Admin', width:100,editable:true,edittype:'select',editoptions:{value:"True:True;False:False"}},
        {name:'Active',index:'Active', width:100,editable:true,edittype:'select',editoptions:{value:"True:True;False:False"}}],
    height: "100%",
    pgbuttons: false,
    pginput: false,
    editurl: 'inc/asp/ajaxUserEditAdd.asp',
    imgpath: 'inc/themes/basic/images',
    subGrid: true,
    subGridRowExpanded: function(subgrid_id, row_id) {
        var subgrid_table_id, pager_id;
        subgrid_table_id = subgrid_id+"_t";
        pager_id = "p_"+subgrid_table_id;
        $("#"+subgrid_id).html("<table id='"+subgrid_table_id+"' class='scroll'></table><div id='"+pager_id+"' class='scroll'></div>"); jQuery("#"+subgrid_table_id).jqGrid({
    url : 'inc/asp/ajaxGridUserAddSubGrid.asp?q='+row_id,
    datatype: "xml",
    height: "100%",
    pgbuttons: false,
    pginput: false,
    imgpath: 'inc/themes/basic/images',
    colNames : ['ID', 'Job', 'Salary'],
    colModel : [
            {name:"ID", index:"ID", width:80,editable:false},
            {name:"Job", index:"Job", width:300,editable:false},
            {name:"Salary", index:"Salary", width:80,editable:true,editoptions:{size:10},editrules:{required:true,number:true}}
            ]
        }).navGrid("#"+pager_id,{edit:true,add:false,del:false,search:false})
    },
    subGridRowColapsed: function(subgrid_id, row_id) {
    // this function is called before removing the data
    //var subgrid_table_id; //subgrid_table_id = subgrid_id+"_t";
    //jQuery("#"+subgrid_table_id).remove(); }
    }
    }).navGrid('#edituserpagergrid',{edit:true,add:true,del:false,search:false});
});

Any help greatly appreciated.