page getting refresh after using update panel

I am using Ajax Rating Control inside my datalist. i used this rating control inside the update panel, so that when user give rate , page wouldn't get refreshed. but still page is getting Refreshed.when user gives rate , then page get refrehed. here is my complete code .

<div class="rating"><asp:UpdatePanel ID="UpPanelRating" runat="server"><ContentTemplate><asp:Rating ID="ratPro" runat="server" AutoPostBack="true" StarCssClass="ratingEmpty" OnChanged="ratPro_Changed"
                                                        WaitingStarCssClass="ratingSaved" EmptyStarCssClass="ratingEmpty" FilledStarCssClass="ratingFilled"></asp:Rating></ContentTemplate></asp:UpdatePanel></div>

what should i do now , so that page don't get refreshed, and user's given star store in database. i just want to stop the page refresh.