ECMAScript For Approval Center

Hi,

I am adding a button in Approval Center Page. i want to show the GUID of the Selected Assignment inside a popup. somethis like the http://msdn.microsoft.com/en-us/library/office/ff535984(v=office.14).aspx#pj14_CustomizeProjectCenter_Testing instead of project center i want inside approval center.

Following is my code, but unfortunately i am not able to fire the event on button click:

/// <reference name="MicrosoftAjax.js"/>
/// <reference path="~/_layouts/inc/pwa/library/Utility.debug.js"/>
/// <reference path="~/_layouts/inc/pwa/library/WebMethodManager.debug.js"/>
/// <reference path="~/_layouts/inc/pwa/library/shell.debug.js"/>
/// <reference path="~/_layouts/inc/pwa/library/TimesheetSatellite.js"/>
/// <reference path="~/_layouts/inc/pwa/library/StatusApprovalsSatellite.js"/>
/// <reference path="~/_layouts/inc/pwa/library/RemoteTextConv.debug.js"/>
/// <reference path="~/_layouts/inc/pwa/library/ProjectFramework.debug.js"/>
/// <reference path="~/_layouts/inc/pwa/library/GridSatellite.debug.js"/>
/// <reference path="~/_layouts/inc/pwa/library/projectserverscripts.debug.js"/>
/// <reference path="~/_layouts/inc/pwa/library/pagepropertymgr.debug.js"/>
/// <reference path="~/_layouts/SP.core.debug.js"/>
/// <reference path="~/_layouts/JsGrid.debug.js"/>
/// <reference path="~/_layouts/JsGrid.Gantt.debug.js"/>
var pc;             // Contains the Project Center extension object.
var toggleMode;     // Maintains state of the toggle button.
_spBodyOnLoadFunctionNames.push("ApprovalCenterMain");
function ApprovalCenterMain() {
    pc = new ApprovalCenterExtension();
    //toggleMode = false;
}
function ApprovalCenterExtension() {
    var _grid;          // Display surface (a view) of the JS Grid.
    var _satellite;     // Control wrapper for the JS Grid.
    // Prevent ECMAScript errors if PJ or the AddGridSatellite function are not defined.
    // If the page is from Project Server, the PJ namespace is defined.
    // If the Project page includes JS Grid, the AddGridSatelliteInitializationNotifier 
    // function is defined.
    if (window.PJ == null || PJ.AddGridSatelliteInitializationNotifier == null) {
        return;
    }
    // Use the PJ.AddGridSatelliteInitializationNotifier function to get an instance 
    // of the satellite.
    PJ.AddGridSatelliteInitializationNotifier
    (
        function (satellite) {
            if (PJ.ProjectCenterSatellite != null) {
                /*** Satellite override: Project code should pass in "satellite" instead of "this". ***/
                satellite = PJ._NotifySatelliteInitComplete.arguments[0];
                _satellite = satellite;
                /***End Satellite override***/
                _grid = satellite.GetJsGridControlInstance();
                _grid.AttachEvent(SP.JsGrid.EventType.OnRowFocusChanged, RowChanged);
            }
        }
    );
    this.DisplaySelectedRecords = function () {
        var selection = _grid.GetSelectedRecordKeys(false);
        var url = "~/_layouts/CustomizeApprovalCenter/SelectedItems.aspx?ProjUIDS=";
        for (var i = 0; i < selection.length; i++) {
            url += selection[i] + "|";
        }
        ShowSPDialog(url);
    }
    function ShowSPDialog(pageToLoad) {
        var options = {
            url: pageToLoad,
            title: 'GUIDs of Selected Tasks',
            showClose: true,
            width: 700,
            height: 250,
            allowMaximize: false,
            dialogReturnValueCallback: NotifyCallBack
        };
        SP.UI.ModalDialog.showModalDialog(options);
    }
    // Show a notification when the modal dialog box is closed.
    function NotifyCallBack(dialogResult, returnValue) {
        SP.UI.Notify.addNotification('Successfully showed selected project GUIDs.');
    }
    // Event handler for the OnRowFocusChanged event in the JS Grid.
    function RowChanged(eventArgs) {
        if (toggleMode) {
            var array = new Array(1);
            array[0] = eventArgs.newRecordKey;
            _satellite._tableCache.GetRecordsByKey(array, GridDataCallBack);
        }
    }
    // Callback function for the RowChanged event handler, which shows an alert dialog box 
    // with the project name.
    function GridDataCallBack(arrayofKeys, arrayofRecords, bSucceeded) {
        alert(arrayofRecords[0].properties["PROJ_NAME"].GetLocalized());
    }
//    this.ToggleMode = function () {
//        if (toggleMode) {
//            toggleMode = false;
//        }
//        else {
//            toggleMode = true;
//        }
//    }
}

Thanks, Parth