Hyperlink not working inside ModalPopupExtender

Hi,

I am trying to display search result in ModalPopupExtender.  I place gridview inside the modal popup to show the result for user query. 

It shows gridview with query result perfectly and when click close button it close successful.

Problem:

As you see i have Hyperlink inside gridview and this navigate to an other page. When user click on hyperlink nothing happened. I place the gridview outside popup and navigate working perfectl.

<div><ajax:ModalPopupExtender ID="mpSearchBooking" runat="server" BackgroundCssClass="ModalPopupBG"
            OkControlID="btnClose" TargetControlID="gvResult" PopupControlID="pnBooking" PopupDragHandleControlID="bookingListPopupHeader"></ajax:ModalPopupExtender><div id="pnBooking" style="display: none; width: 650px;" class="popupConfirmation"><div class="popup_Container"><div class="popup_Titlebar" id="bookingListPopupHeader"><asp:Label ID="lbSearchingHeading" runat="server"></asp:Label></div><div class="popup_Body" style="overflow-y: scroll; height: 200px; width: 600px;"><asp:GridView ID="gvResult" runat="server" AutoGenerateColumns="False" CssClass="mGrid"
                        DataKeyNames="BookingID,Datum" Width="98%" HorizontalAlign="Center"><Columns><asp:HyperLinkField DataNavigateUrlFields="bookingID,Datum" DataNavigateUrlFormatString="~/conferenceSchema/bookingDetail.aspx?bookingID={0}&amp;BookingDate={1}" HeaderText="Datum" DataTextField="Datum" Target="_blank" HeaderStyle-HorizontalAlign="Left" ItemStyle-HorizontalAlign="Left" /><asp:BoundField DataField="Building" HeaderText="Building" HeaderStyle-HorizontalAlign="Left" ItemStyle-HorizontalAlign="Left" /><asp:BoundField DataField="Kund" HeaderText="Kund" HeaderStyle-HorizontalAlign="Left" ItemStyle-HorizontalAlign="Left" /><asp:BoundField DataField="Tid" HeaderText="Tid" HeaderStyle-HorizontalAlign="Right" ItemStyle-HorizontalAlign="Right" /><asp:BoundField DataField="Antal" HeaderText="Antal" HeaderStyle-HorizontalAlign="Right" ItemStyle-HorizontalAlign="Right" DataFormatString="{0:N}" /><asp:BoundField DataField="Rumshyra" HeaderText="Rumshyra" HeaderStyle-HorizontalAlign="Right" ItemStyle-HorizontalAlign="Right" DataFormatString="{0:N}" /></Columns></asp:GridView></div><div class="popup_Buttons"><input id="btnClose" value="Stänga" type="button" /></div></div></div></div>