Problema con postback

[Mechis79]

Hola, gracias por atender ;)

Código:

<td align="left">
                        <asp:Button ID="ButtonSearch" runat="server" BorderStyle="Solid" BorderWidth="1px"
                            BackColor="White" BorderColor="#507CD1" ForeColor="#284E98" Height="24px"
                            Text="Buscar" onclick="ButtonSearch_Click" />
                             &nbsp;&nbsp;</td>