Unable to get the BaloonPopupExtender to work with the ToggleButtonExtender for a checkbox

I started using the ToggleButtonExtender for my checkboxes to custumize their appearance. At the same time I've been using the BaloonPopupExtender on other controls as a fancy tooltip of sorts. But I cannot get these extenders to work together to save my life. They work fine independently, but if used like below, the BaloonPopup never shows.

Any ideas please?

<asp:CheckBox ID="ckAction" runat="server" checked='<%# Bind("action") %>' ToolTip="Check/uncheck the sessions you want to participate in and then click the [Next Step] or [Checkout] button below to continue."
                        visible='<%# eval("atendeeid")>0 %>' /><asp:BalloonPopupExtender ID="BalloonPopupExtender2" runat="server" BalloonPopupControlID="pnNotice4" DisplayOnClick=true
                            CustomCssUrl="" DynamicServicePath="" Enabled="True" ExtenderControlID="" DisplayOnFocus=true DisplayOnMouseOver=true  BalloonSize=Medium
                            TargetControlID="ckAction"></asp:BalloonPopupExtender><asp:Panel ID="pnNotice4" runat="Server" visible='<%# eval("atendeeid")>0 %>'><asp:Label ID="Label2" runat="server" Text="Check/uncheck the sessions you want to participate in and then click the [Next Step] or [Checkout] button below to continue."></asp:Label></asp:Panel><asp:ToggleButtonExtender ID="gvMasterPackages_chkRegister_ToggleButtonExtender0"
                        runat="server" CheckedImageUrl="images/checkbox_checked.ico"
                        DisabledCheckedImageUrl="images/checkbox_checked_d.ico"
                        DisabledUncheckedImageUrl="images/checkbox_unchecked_d.ico" Enabled="True"
                        ImageHeight="24" ImageWidth="24" TargetControlID="ckAction"
                        UncheckedImageUrl="images/checkbox_unchecked.ico"></asp:ToggleButtonExtender>