a few example snippets below, first one, .length is being flagged as unknown var val:String = value ? String(value) : ""; if (results.length > 0 || ((val.length == 0) && !required)) second one .text is being flagged as unknown public class DobValidator extends DateValidator { // Constructor. public function DobValidator() { // Call base class constructor. super(); } // Define the doValidation() method. override protected function doValidation(value:Object):Array { // Call base class date validation var results:Array = super.doValidation(value); // verify DOB not in future if there are no errors. if (results.length == 0 && Date.parse(daySource.text + "/" + monthSource.text + "/" + yearSource.text) > new Date()) {