Is it possible to use NetworkServer.Spawn(obj) in animator state?

Hey, i want to spawn object when animation A is enter. As in title is it possible to create object like that?

public class MudWallSpawn : StateMachineBehaviour

...

Transform pozycja = kawson.SkryptAnimacji.pozycjaGracza;

        //pozycja.transform.position 

        Vector3 pos = new Vector3(pozycja.transform.position.x, pozycja.transform.position.y - 16f, pozycja.transform.position.z);

        GameObject gameobject = Instantiate(objekt, (pozycja.transform.forward * 20f) + pos, pozycja.transform.rotation * objekt.transform.rotation);

        NetworkServer.Spawn(gameobject);

If i use NetworkServer.Spawn(gameobject); i got "did you forget to add it to NetworkManager?"
Without it when i create object, it spawn front of each player instead in 1 position front off player who spawn it.