jQuery Grid Plugin - jqGrid

Hi all,

I have one jqGrid which initially passes some empty parameters for the web service and returns an empty row.
After that, end user inputs those parameters where there is another AJAX call which calls this same web service every minute.

I see the parameters being passed and the values being returned (via fiddler2) but they are not being displayed at the grid.
Here is the stripped out code:

  var UpdateDatabaseSetupGridTimeout = null;
  var UpdateDatabaseSetupGridTimeoutLength = 5000;
  var DatabaseSetupGridJqueryID = "#DatabaseSetupGrid";

  function DatabaseSetupGrid_Load()
  {
      //Initialize Collection and Advertisement with n/a
      $("#hiddenDatabaseCollectionID").val("n/a");
      $("#hiddenDatabaseAdvertisementID").val("n/a");
...
      $(DatabaseSetupGridJqueryID).jqGrid
    ({
        autowidth: true,
        rowNum: 1000,
        caption: "Test"
        colModel:
        [
            { name: 'ResourceID', index: 'ResourceID', sortable: false, resize: false, align: "center", width: 100, hidden: true },
            { name: 'Name', index: 'Name', sortable: false, resize: false, align: "center" },
        ],
        colNames: ['ResourceID', 'Name'],
        datatype: 'json',
        beforeProcessing: function () {

            //update CollectionID and AdvertisementID statuses on jqGrid Title Bar
            $("#DatabaseCollectionID").text($("#hiddenDatabaseCollectionID").val());
            $("#DatabaseAdvertisementID").text($("#hiddenDatabaseAdvertisementID").val())
        },
        gridComplete: function () {
            UpdateDatabaseSetupGridTimeout = setTimeout("UpdateDatabaseSetupGrid()", UpdateDatabaseSetupGridTimeoutLength);
        },

        height: "100%",
        hidegrid: true,
        jsonReader:
        {
            repeatitems: false,
            id: "ResourceID",
            root: function (obj) {
                return obj;
            }
        },
        onSelectRow: function () {
            $("#" + this.id).resetSelection()
        }
        , url: "Administration.svc/GetCollectionMembers?CollectionID=" + $("#hiddenDatabaseCollectionID").val() + "&AdvertisementID=" + $("#hiddenDatabaseAdvertisementID").val()
    });
  }

  ////////////////////////////////////////////////////////////////////////////////////
  //THIS IS CALLED EVERY MINUTE - I SEE THE DATA RETURNED BUT THE GRID IS NOT UPDATED
  ////////////////////////////////////////////////////////////////////////////////////
  function UpdateDatabaseSetupGrid() {

      alert("UpdateDatabaseSetupGrid");
      $.ajax
      ({
          async: false
        , cache: false
        , dataType: "json"
        , beforeSend: function (jqXHR, settings) {
            //alert(settings.url)
        }
        , error: function (jqXHR, textStatus, errorThrown) {
            clearTimeout(UpdateDatabaseSetupGridTimeout);
            alert("Grid ajax error:\r\n" + errorThrown)
        }
        , success: function (data, textStatus, jqXHR) {
            //var databaseSetupGrid = $(DatabaseSetupGridJqueryID);
            ...
        }

//        ,jsonReader:
//         {
//            repeatitems: false,
//            id: "ResourceID",
//            root: function (obj) {
//                return obj;
//            }
//         }
        , url: "Administration.svc/GetCollectionMembers?CollectionID=" + $("#hiddenDatabaseCollectionID").val() + "&AdvertisementID=" + $("#hiddenDatabaseAdvertisementID").val()
      });

      UpdateDatabaseSetupGridTimeout = setTimeout("UpdateDatabaseSetupGrid()", UpdateDatabaseSetupGridTimeoutLength);
  }
  </script>

Thanks for any help you can provide.