[v3.0beta2] i have question for ActionTween

cocos2d-x C++
#1

i try to filp the sprite use ActionTween

 Sprite* testSprite = (Sprite*)getChildByTag(1);
 ActionTween* fliptest = ActionTween::create(2.0f, "scaleX", 1, -1);
 testSprite->runAction(fliptest);

but have the err in CCActionTween.cpp

CCASSERT(dynamic_cast<ActionTweenDelegate*>(target), "target must implement ActionTweenDelegate");

somebody help me pls…