jQuery Grid Plugin - jqGrid

I am currently trying to get virtual paging to work.  Normal paging (option scroll: 0) works fine but when I use scroll: 1 to enable virtual paging my grid shows 980 blank lines,  followed by the 20 lines provided by the server.  Is my server not providing the correct format or am I doing something else wrong?  My configuration and sample data is included below.

Thank you in advance,

Shawn

SAMPLE DATA

{"page":"1","total":50,"records":1000,

"rows":[{"id":1,"cell":[1,"admin","Administrator","admin@example.com",1,

"2012-07-17T03:56:58.975Z","2012-07-17T03:56:58.975Z",""]},

{"id":1002,"cell":[1002,"test","test","test@test.com",1,

"2012-07-17T03:59:35.947Z","2012-07-17T03:59:35.947Z",""]},

{"id":2,"cell":[2,"test0","Administrator","admin@example.com",1,

"2012-07-17T00:24:55.098Z","2012-07-17T00:24:55.098Z",""]},

{"id":3,"cell":[3,"test1","Administrator","admin@example.com",1,

"2012-07-17T00:25:07.169Z","2012-07-17T00:25:07.169Z",""]},

{"id":117,"cell":[117,"test115","Administrator",

... total of 20 rows ...

"admin@example.com",1,"2012-07-17T00:25:07.274Z","2012-07-17T00:25:07.274Z",""]}]}

CONFIGURATION

      $("#users").jqGrid({
        url: "users/jqGrid.json",
        editurl: "/users",
        datatype: "json",
        caption: "Users",
        hidegrid: false,
        gridview: false,
        shrinkToFit: true,
        autowidth: true,
        sortname: 'user_name',
        sortorder: "asc",
        loadonce: false,
        scroll: 1,
        rowNum: 20,
        pager: "#pager",
        viewrecords: true,
        colModel: [
          {
            name: 'id',
            label: "Id",
            width: 50,
            align: "center"
          }, {
            name: 'user_name',
            label: "User Name",
            width: 100,
            editable: true,
            editrules: {
              required: true
            },
            editoptions: {
              width: "100%"
            }
          }, {
            name: 'display_name',
            label: "Display Name",
            width: 200,
            editable: true,
            editrules: {
              required: true
            }
          }, {
            name: 'email_address',
            label: "Email Address",
            width: 200,
            editable: true,
            editrules: {
              required: true,
              email: true
            }
          }, {
            name: 'admin',
            label: "Admin?",
            width: 50,
            editable: true,
            formatter: "checkbox",
            edittype: "checkbox",
            editoptions: {
              value: "true:false"
            }
          }, {
            name: 'created',
            label: "Date Created",
            width: 200
          }, {
            name: 'last_updated',
            label: "Last Updated",
            width: 200
          }, {
            name: 'password',
            label: "Password",
            hidden: true,
            editable: true,
            editrules: {
              edithidden: true,
              required: false
            }
          }
        ]
      });