Error: Call to a possibly undefined method X Among other reasons, this error could be the result of not following the AS3 naming conventions for packages, classes, methods, variables, and so on. For example, can you spot the mistake here? (The answer is in this footnote * ) package controller { import model.MyModel; import org.robotlegs.mvcs.Command; public class MyCommand extends Command { [Inject] public var model:MyModel; override public function execute():void { model.myMethod(); } } } would result in: 1. Error 1180: Call to a possibly undefined method myMethod 2. Warning 3599: Definition name is the same as an imported package name