Метод getDistance () не работает в Cocos2d-x

// — Совместное создание.

auto fixedjointleft = PhysicsJointDistance::construct(upperbody, leftbody, upperbody->getPosition(),leftbody->getPosition() );

auto fixedjointright = PhysicsJointDistance::construct(upperbody, rightbody, upperbody->getPosition(), rightbody->getPosition());

auto jointgear = PhysicsJointGear ::construct(leftball->getPhysicsBody(), rightball->getPhysicsBody(), 200.0,4.0);

// — Добавление в PhysicsWorld

physics_world->addJoint(jointgear);
physics_world->addJoint(fixedjointleft);
physics_world->addJoint(fixedjointright);

CCLOG("  distance = %f", fixedjointleft->getDistance());