<asp:TemplateField HeaderText="Start TTSN">
                                            <ItemTemplate>
                                                <asp:Label ID="Label2" runat="server" Text='<%# Bind("StartTTSN", "{0:D}") %>'/>
                                            </ItemTemplate>
                                            <EditItemTemplate>
                                                <asp:TextBox ID="TextBox2" runat="server" 
                                                    Text='<%# Bind("StartTTSN", "{0:D}") %>' ReadOnly="False" />
                                                   <asp:RangeValidator runat="server" Type="Integer" MinimumValue="0" />
                                            </EditItemTemplate>
                                            
                                            
                                        </asp:TemplateField>