validation expression

[new SE]

Hi all..i need some help please..i'm doing a validation using a validation expression..this is use to make a user just input the digit in 5 digit..
i'm using this now but not function

<tr>
        <td class="style1">Zip Code </td>
        <td>:</td>
        <td>
            <asp:TextBox ID="txtCmpZip" runat="server" BorderStyle="Groove" MaxLength="5"></asp:TextBox><asp:RequiredFieldValidator ID="CmpZip" runat="server" ErrorMessage="*" ControlToValidate="txtCmpZip"></asp:RequiredFieldValidator>
            <asp:RegularExpressionValidator ErrorMessage="Zip code must be 5 numeric digits" ValidationExpression="\d{5}" EnableClientScript="False" runat="server" ControlToValidate="txtCmpZip"></asp:RegularExpressionValidator>
        </td>
    </tr>

[dnanetwork]

http://msdn.microsoft.com/en-us/library/ms972966.aspx

^\d{5}$

// Done

[samkaraja]

do you set auto bostback property for your textbox.