cant center a panel

hello, im trying to center the content of a panel, it works for the first but not the second, both are in the same <td> with justify text-align


<asp:Panel ID="panMailing" runat="server">
                    <!-- center works corectly -->  

                    <div style="text-align:center;">
                    <asp:RequiredFieldValidator ID="rfMail" runat="server" ErrorMessage="inserire il proprio indirizzo e-mail" ControlToValidate="txtMail" Display="Dynamic"></asp:RequiredFieldValidator><asp:RegularExpressionValidator ID="reMail&qu ...