Whole page refreshes with update panel rather than just the content area

[ra220511]

hello ive only started using ajax for first time today . i am trying to use an update panel in asp.net but my whole page keeps refresh rather than just the content area. can any one help.

<asp:Panel id="pnlQA" runat="server">
                                        <asp:UpdateProgress ID="upcQuestionnaire" runat="server">
                                            <ProgressTemplate>
                                                <div>
                                                    <img src="images/indicator.gif" alt="" />
                                                    Updating...
                                                </div>
                                            </ProgressTemplate>
                                        </asp:UpdateProgress>
                                        <asp:UpdatePanel ID="upPanel" runat="server">
                                            <ContentTemplate>
                                                    <br />  
                                                    <asp:table ID="tblChoice" runat="server" Width="100%">
                                                        <asp:TableRow>
                                                            <asp:TableCell ColumnSpan="2" HorizontalAlign="center" Height="50px"><b><asp:Label ID="lblIntro" runat="server" ></asp:Label></b></asp:TableCell>
                                                        </asp:TableRow>
                                                        <asp:TableRow>
                                                            <asp:TableCell ColumnSpan="2" HorizontalAlign="center" Height="50px"><span style="color:Red;"><b>Question <asp:Label ID="lblPageCount" Text="1" runat="server"></asp:Label> of <asp:Label ID="lblQuestionCount" runat="server"></asp:Label></b></span></asp:TableCell>
                                                        </asp:TableRow>
                                                        <asp:TableRow>
                                                            <asp:TableCell ColumnSpan="2"><b>Question: </b><asp:Label ID="lblQuestion" runat="server" ></asp:Label><asp:Label ID="lblDisplayOrder" runat="server" Visible="false"></asp:Label><br /><br /></asp:TableCell>
                                                        </asp:TableRow>
                                                        <asp:TableRow>
                                                            <asp:TableCell ColumnSpan="2">&nbsp;&nbsp;&nbsp;<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="radAnswers" ErrorMessage="*Pleae choose one option" /></asp:TableCell>
                                                        </asp:TableRow>
                                                        <asp:TableRow>
                                                            <asp:TableCell><img src="Images/Spacer.gif" width="20px" alt="" /></asp:TableCell>
                                                            <asp:TableCell><asp:RadioButtonList ID="radAnswers" runat="server" CssClass="PollOptions" /></asp:TableCell>
                                                        </asp:TableRow>
                                                        <asp:TableRow><asp:TableCell><br /></asp:TableCell></asp:TableRow>
                                                        <asp:TableRow>
                                                            <asp:TableCell ColumnSpan="2"  Height="50px"><b>Comment:</b> <br /><asp:TextBox ID="txtComment" runat="server" Width="75%" TextMode="MultiLine" Height="100px"></asp:TextBox></asp:TableCell>
                                                        </asp:TableRow>
                                                    </asp:table>
                                            </ContentTemplate>
                                            <Triggers >
                                                <asp:AsyncPostBackTrigger ControlID="cmdSubmit" EventName="click" />
                                            </Triggers>
                                        </asp:UpdatePanel>
                                        <img src="images/spacer.gif" alt="" width="150px" height="1px"/><asp:imagebutton ID="cmdSubmit" runat="server" AlternateText="Next" ImageUrl="Images/next.gif" />
                                    </asp:Panel>