birthday comparing todays date

Code Behind
The Sample Code is a Small Function to check wether Birthday is greater than todays date.

If Trim(txtBirthDate.Text) = "" Then
        Else
            Dim textboxdate As Date = Convert.ToDateTime(txtBirthDate.Text).Date
            Dim todaysdate As Date = DateTime.Now.Date
            If textboxdate >= todaysdate Then
                datelabel.Visible = True
                datelabel.Text = "Birth date must Not be greater than today's Date"
                flag = False
            End If
        End If

          < td width="68%" align="left" style="width: 510px" > 
          < div id="datediv" runat="server" visible="true" class="validation3" > 
           < asp:Label ID="datelabel" runat="server" Visible="True" >  < /asp:Label > 
          < /div > 
         < /td >