I recently downloaded and installed Roo-Gwt

Version: 2.3.3.M1
Build Id: 201005170052

When I run the sample 'expenses' application and load following link in browser, I am getting error.

http://127.0.0.1:8888/ApplicationSca...7.0.0.1:999 7

Error stack is below. Any one has clue what is going on?

Thanks..

Caused by: com.google.gwt.core.client.JavaScriptException: (TypeError): '$wnd.JSON' is null or not an object
number: -2146823281
description: '$wnd.JSON' is null or not an object
at com.google.gwt.dev.shell.BrowserChannelServer.invo keJavascript(BrowserChannelServer.java:247)
at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke (ModuleSpaceOOPHM.java:120)
at com.google.gwt.dev.shell.ModuleSpace.invokeNative( ModuleSpace.java:510)
at com.google.gwt.dev.shell.ModuleSpace.invokeNativeO bject(ModuleSpace.java:264)
at com.google.gwt.dev.shell.JavaScriptHost.invokeNati veObject(JavaScriptHost.java:91)
at com.google.gwt.requestfactory.client.impl.ClientRe questHelper$MyJSO$.toJsonString$(ClientRequestHelp er.java)
at com.google.gwt.requestfactory.client.impl.ClientRe questHelper$MyJSO$.access$1(ClientRequestHelper.ja va:44)
at com.google.gwt.requestfactory.client.impl.ClientRe questHelper.getRequestString(ClientRequestHelper.j ava:54)
at com.springsource.extrack.gwt.request.EmployeeReque stImpl$3.getRequestData(EmployeeRequestImpl.java:3 1)
at com.google.gwt.requestfactory.client.impl.RequestF actoryJsonImpl.fire(RequestFactoryJsonImpl.java:57 )
at com.google.gwt.requestfactory.client.impl.Abstract Request.fire(AbstractRequest.java:47)
at com.springsource.extrack.gwt.ui.EmployeeListActivi ty.fireCountRequest(EmployeeListActivity.java:92)
at com.google.gwt.valuestore.ui.AbstractRecordListAct ivity.init(AbstractRecordListActivity.java:192)
at com.google.gwt.valuestore.ui.AbstractRecordListAct ivity.start(AbstractRecordListActivity.java:140)
at com.springsource.extrack.gwt.ui.EmployeeListActivi ty.start(EmployeeListActivity.java:83)
at com.google.gwt.app.place.ActivityManager.onPlaceCh ange(ActivityManager.java:113)
at com.google.gwt.app.place.PlaceChangeEvent.dispatch (PlaceChangeEvent.java:58)
at com.google.gwt.app.place.PlaceChangeEvent.dispatch (PlaceChangeEvent.java:1)
at com.google.gwt.event.shared.HandlerManager$Handler Registry.fireEvent(HandlerManager.java:78)
at com.google.gwt.event.shared.HandlerManager$Handler Registry.access$1(HandlerManager.java:55)
at com.google.gwt.event.shared.HandlerManager.fireEve nt(HandlerManager.java:208)
at com.google.gwt.app.place.PlaceController.goTo(Plac eController.java:43)
at com.google.gwt.app.place.PlacePicker.placePicked(P lacePicker.java:43)
at com.google.gwt.app.place.PlacePicker.placePicked(P lacePicker.java:1)
at com.google.gwt.app.client.CellListPlacePickerView$ 1.onSelectionChange(CellListPlacePickerView.java:5 8)
at com.google.gwt.view.client.SelectionModel$Selectio nChangeEvent.dispatch(SelectionModel.java:99)
at com.google.gwt.view.client.SelectionModel$Selectio nChangeEvent.dispatch(SelectionModel.java:1)
at com.google.gwt.event.shared.HandlerManager$Handler Registry.fireEvent(HandlerManager.java:78)
at com.google.gwt.event.shared.HandlerManager$Handler Registry.access$1(HandlerManager.java:55)
at com.google.gwt.event.shared.HandlerManager.fireEve nt(HandlerManager.java:208)
at com.google.gwt.view.client.SelectionModel$Abstract SelectionModel.fireEvent(SelectionModel.java:126)
at com.google.gwt.view.client.SelectionModel$Selectio nChangeEvent.fire(SelectionModel.java:70)
at com.google.gwt.view.client.SelectionModel$Abstract SelectionModel$1.execute(SelectionModel.java:159)
at com.google.gwt.core.client.impl.SchedulerImpl$Task $.executeScheduled$(SchedulerImpl.java:50)
at com.google.gwt.core.client.impl.SchedulerImpl.runS cheduledTasks(SchedulerImpl.java:229)
at com.google.gwt.core.client.impl.SchedulerImpl.flus hFinallyCommands(SchedulerImpl.java:328)
at com.google.gwt.core.client.impl.Impl.exit(Impl.jav a:238)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gwt.dev.shell.ModuleSpace.onLoad(Module Space.java:377)
at com.google.gwt.dev.shell.OophmSessionHandler.loadM odule(OophmSessionHandler.java:181)
at com.google.gwt.dev.shell.BrowserChannelServer.proc essConnection(BrowserChannelServer.java:520)
at com.google.gwt.dev.shell.BrowserChannelServer.run( BrowserChannelServer.java:362)
at java.lang.Thread.run(Thread.java:619)