I can't make transition from actual animation to previous one

Evening! I have some trouble at calling transition. I can make the transition from up to down but i cant go from down to up. As you can see in Nest picture i make all transition, but only those who came from up are able to be called. The script I'm using is here :

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 
 public class AnimatorController : MonoBehaviour
 {
 
     int pagNr = 1;
     int BackPag=99;
     public Animator anim;
 
    
 
     void Start()
     {
         anim = GetComponent<Animator>();
         Debug.Log(BackPag);
         Debug.Log(pagNr);
     }
 
     // Update is called once per frame
     void Update()
     {
        
 
         if (Input.GetKeyDown(KeyCode.KeypadEnter) || Input.GetKeyDown(KeyCode.Space) || Input.GetKeyDown(KeyCode.RightArrow))
         {
            
                 pagNr++;
                 BackPag++;
                 anim.SetInteger("PAg", pagNr);
                 Debug.Log(BackPag);
                 Debug.Log(pagNr);
                 //anim.SetTrigger("EnterPag1");}
 
             
 
            
 
         }
         if (Input.GetKeyDown(KeyCode.LeftArrow))
             {
                
                     BackPag--;
                    pagNr--;
             anim.SetInteger("PAg", pagNr);
             anim.SetInteger("BackPag", BackPag);
             Debug.Log(" ");
             Debug.Log(BackPag);
             Debug.Log(pagNr);
             Debug.Log(" ");
 
         }
     }
    
 }

Please try to respond as fast as you can!

Thanks in advance!

NOTE: PAg is trigger for up-down transitions and BackPag is for down-up transition!

P.S. Sorry for my english, I'm not so good at it :)

Serju