Validation Summary from Modal Popup

I ave a modal popup that opoens wheni  user wants to log a ride.  The ride date cannot be in the future or more than 2 weeks past. I use a range validator for this. owever, when i click on the insert button it does not display the error in the validation summary. I have the DiIsplay property set to None and associated with the validation group. If Ichange it to Dynamic it is displayed correctly within the form, but not in the summary. I changed the validation to check if the Page is valid and Show the popup if it is not, but the error is not displayed.

The HTML:

<InsertItemTemplate><table class="auto-style4"><tr><td class="tdlt_50" colspan="5"><asp:ValidationSummary ID="vgrpadd" runat="server" ShowSummary="true" DisplayMode="BulletList" /></td><td>&nbsp;</td></tr><tr><td class="tdlt_50">&nbsp;</td><td class="tdrt_100">Date:</td><td class="tdlt_100"><asp:TextBox ID="tbdate" runat="server" CssClass="tdlt_75"
                                        Text='<%# Bind("ridedate") %>' Width="65px" /><ajaxToolkit:CalendarExtender ID="TextBox2_CalendarExtender"
                                        runat="server" Enabled="True" PopupButtonID="imgcal" TargetControlID="tbdate" />&nbsp;<asp:ImageButton ID="imgcal" runat="server" ImageUrl="~/Images/Icons/calendar_1.png" /><asp:RangeValidator ID="RangeValidator1" runat="server" ControlToValidate="tbdate"
                                        ErrorMessage="You cannot future date a ride or enter one more than 2 Months old" Display="None" ValidationGroup="vgrpadd" /></td>

The code:

 protected void InsertButton_Click(object sender, EventArgs e)
   {
        Page.Validate();
        if (!IsValid)
        {
            RangeValidator Range = (RangeValidator)FormView1.FindControl("RangeValidator1");
            DateTime dtnowdt = DateTime.Today;
            TextBox tbrdate = (TextBox)FormView1.FindControl("tbdate");

            string dtnow = dtnowdt.ToShortDateString();
            //tbrdate.Text = dtnow;
            string dtmin = DateTime.Today.AddDays(-14).ToShortDateString();

            ValidationSummary vs = (ValidationSummary)FormView1.FindControl("vgrpadd");

            tbrdate.Text = dtnow;

            Range.MaximumValue = dtnow;
            Range.MinimumValue = dtmin;

            Range.Type = ValidationDataType.Date;
            Range.Display = ValidatorDisplay.None;
            Range.ValidationGroup = "vs";
            Range.ErrorMessage = "You cannot future date a ride or enter one more than 2 Weeks old";
            mpe_detail.Show();
        }
           if (IsValid)
           {
               mpe_detail.Hide();
           }
   }