jQuery Grid Plugin - jqGrid

If I load the grid with 400+ records, I'm trying to figure out a way to not have to hit the server everytime I go to the next page.  It is my understanding that if I set loadonce:true then that should do the trick.  However, everytime I change the page I see the webservice being called.

Is my understanding of this functionality wrong?    My code is below.

jQuery(document).ready(function () {
    jQuery("#list").jqGrid({
        datatype: processrequest,
        mtype: 'POST',  
        jsonReader: {  
            repeatitems: false,  
            id: "name" //index of the column with the PK in it   
        },
        colNames: ['Name', 'Title'],
        colModel: [
      { name: 'name', index: 'name', width: 250 },
      { name: 'title', index: 'title', width: 250 }
      ],
        pager: '#pager',
        rowNum: 10,
        rowList: [10, 20, 30],
        sortorder: "desc",
        viewrecords: true,
        height: '250px',
        caption: 'My first grid',
        loadonce: true
    }).navGrid('#pager', {edit: false, add: false, del: false});
});

function processrequest(postdata) {
    $(".loading").show();
    $.ajax({
        type: "POST",
        data: "{}",
        datatype: "json",
        url: "../webServices/myTestWS.asmx/testMethod",
        contentType: "application/json; charset-utf-8",
        complete: function (jsondata, stat) {
            if (stat == "success") {
                var thegrid = jQuery("#list")[0];
                var jsonObject = (eval("(" + jsondata.responseText + ")"));
                thegrid.addJSONData(jsonObject.d);
                $(".loading").hide();
            } else {
                $(".loading").hide();
                alert("Error with AJAX callback");
            }
        }
    });
}