Armatue 截图为什么截不了？

Cocos2d-x
#1

Armature *arma = Armature::create("123");

this->addChild(arma);


auto renderer = Director::getInstance()->getRenderer();
Mat4 parentTransform = Director::getInstance()->getMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
Size size = role->getContentSize();

RenderTexture* armaRt = RenderTexture::create(size.width, size.height, Texture2D::PixelFormat::RGBA8888);
armaRt->begin();
arma->visit(renderer, parentTransform, true);
armaRt->end();
这样为什么截图了图？？