trying to add scollbar in panel containing gridview but it is not working

<form id="form1" runat="server">

  <asp:ToolkitScriptManager  ID="manager" runat="server"></asp:ToolkitScriptManager>
  <asp:Button ID="button1" runat="server"  Text="open pop up"
       onclick="button1_Click"/>
  <asp:Panel ID="panel1" runat="server" ScrollBars="Both"   AutoScroll="true" Wrap="True" Direction="LeftToRight">

 <asp:GridView ID="grdvw" runat="server"
                   AutoGenerateColumns="False"
                   DataKeyNames="crop_code" Width="100%"
             BackColor=White>

               <Columns>
               <asp:TemplateField>
                   <ItemTemplate>
                       <asp:RadioButton ID="radiobutton1" runat="server" />

                   </ItemTemplate>
               </asp:TemplateField>

                   <asp:BoundField HeaderText="crop code" DataField="crop_code" />
                   <asp:BoundField DataField="season" HeaderText="season" />

               </Columns>
               <EmptyDataTemplate>
                   No Data Found...<br />
               </EmptyDataTemplate>
           </asp:GridView>
  <asp:Button runat="server" ID="ok"  Text="ok:"  />



  </asp:Panel>
  <asp:TextBox runat="server" ID="txtbox1"></asp:TextBox>
   <asp:ModalPopupExtender ID="ModalPopupExtender1" runat="server" PopupControlID="panel1" OnOkScript="ok" TargetControlID="button1" BackgroundCssClass="modalbackground">
    </asp:ModalPopupExtender>
   </form>