validation of panel and radiobutton list using javascript

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VB

ASP.NET

Javascript

C#3.5

HI
I have a webform like:

<asp:Panel ID="pnlLbl" runat ="server" Visible ="false" >
     <asp:RadioButtonList ID="RadioButtonList1" runat="server" RepeatDirection="Horizontal">
         <asp:ListItem>Yes</asp:ListItem>
         <asp:ListItem>No</asp:ListItem>
     </asp:RadioButtonList>

     <asp:RadioButtonList ID="RadioButtonList2" runat="server" RepeatDirection="Horizontal">
         <asp:ListItem>Yes</asp:ListItem>
         <asp:ListItem>No</asp:ListItem>
     </asp:RadioButtonList></asp:Panel>
      <br /><asp:Button ID="Button1" runat ="server" Text="submit" />

Now I have to return false value if pnlLbl=visible and if none of the radiobuttonlist is selected, through javascript.

Please suggest.