Weld Joint not working. Changing a rigidbody from dynamic to kinematic crashes cocos (box2d)

Cocos Creator
#1

i have an object falling and in the bottom an object moving. i want that the object falling when it collides it sticks to the moving object.
https://snag.gy/SAlNga.jpg
the result is that falling object bounces.never sticks. It keeps moving and then falls.
i tried setting the sphere rigidbody from dynamic to kinematic so can attach using set parent, but Box2d crashes.

onPostResolve (contact, selfCollider, otherCollider)
{

    console.log(otherCollider);

    if(otherCollider.node.name=="Player"  && ! this.bIsSticked  && this.bCanStick)
    {
        this.bIsSticked=true;
        this.bCanStick=true;
     //   otherCollider.getComponent("PlayerController").addSnowBall(this.node);
     this.rb.linearVelocity=new cc.Vec2(0,0);
      let joint=  this.node.getComponent(cc.WeldJoint);
        

        let arrowBody = selfCollider.body;
        let targetBody = otherCollider.body;
        let worldCoordsAnchorPoint = arrowBody.getWorldPoint( cc.v2(0.6, 0) );
    
        joint.connectedBody = targetBody;
        joint.anchor = arrowBody.getLocalPoint( worldCoordsAnchorPoint );
        joint.connectedAnchor = targetBody.getLocalPoint( worldCoordsAnchorPoint );
        joint.referenceAngle = targetBody.node.rotation - arrowBody.node.rotation;
      
        joint.enabled = true;
      joint.apply();
      


    }
}