My Button Only follows half of the commands.

 public Button FriendButton;
     
     public void BusinessButton ()
     {
         LifeTx.text = "Business Life";
         BusinessTabBool = true;
         PersonalTabBool = false;
 
         FriendButton.enabled = false;
         FriendButton.gameObject.SetActive (false);
 
     }
 
     public void PersonalButton ()
     {
         LifeTx.text = "Personal Life";
         PersonalTabBool = true;
         BusinessTabBool = false;
 
         FriendButton.enabled = true;
         FriendButton.gameObject.SetActive (true);
 
     }

The LifeTx part of the button works great. The Bools work but in the inspector it doesn't show them turning on or off. But I am trying to turn another button on and off with a different button and that is not working at all. It gives the error "Object reference not set to an instance of an object" every time I try and use it. But, I am setting which button I want to turn on and off in the inspector window.