Regular Expression Validator For Date Format Validation for ASP.Net TextBox

<asp:TextBox ID="TextBox1" runat="server" AutoPostBack = "true" CausesValidation = "true"></asp:TextBox>
    <asp:RegularExpressionValidator ID="RegularExpressionValidator1" ControlToValidate = "TextBox1" 
    ValidationExpression = "^(0?[1-9]|[12][0-9]|3[01])[\/\-](0?[1-9]|1[012])[\/\-]\d{4}$" 
    runat="server" ErrorMessage="Invalid Date format. Valid Date Format dd/MM/yyyy">
    </asp:RegularExpressionValidator>

Validates dd/mm/yyyy format