protected override void CreateChildControls()
{
base.CreateChildControls();
_regexValidator = new RegularExpressionValidator();
_regexValidator.ID = this.ID + "_RE";
_regexValidator.ControlToValidate = this.ID;
_regexValidator.Display = ValidatorDisplay.Dynamic;
_regexValidator.CssClass = "validation-error help-inline";
_regexValidator.ValidationExpression = @"\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*";
_regexValidator.ErrorMessage = "The email address provided is not valid";
Controls.Add( _regexValidator );
}