Monobehaviour problem

jubei.cs

class State: Monobehaviour {
  
  //reference to the state we will need to jump to
  public State nextState;
  
  protected virtual void Update()
  {
    if (mouseClicked) 
	{ 
		doSomething();
		advance();
	}
  } 
  
  protected abstract void doSomething();
  
  public virtual void advanceState()
  {
        //disable this state (i.e. update will stop being called)
        enabled = false;

        //enable the next one
        nextState.Activate();
  }
  
  public virtual void Activate()
  {
      this.enabled = true;
  }

}

//First child state
class FirstState: State {

  protected override void doSomething() 
  {
    Debug.Log("FirstState");
  }
}

//second child state
class SecondState: State {

 protected override void doSomething() 
  {
    Debug.Log("SecondState");
  }
}


//output in console when advancing from firstState to secondState:
FirstState
SecondState