why CBehavior::setEnabled() deos not work

why CBehavior::setEnabled() deos not work

Provide us more info please? :)




               // MyComponent is a child class of Component

                // Grow and Play extends CBehavior

                $grow = new MyComponent;

                $gBehavior = new Grow;

                $pBehavior = new Play;

                $grow->attachBehavior('grow',$gBehavior);

                $grow->attachBehavior('play',$pBehavior);

                $grow->disableBehavior('play'); //why does this step not work

                $grow->run();