UI Prev button

Hi I wrote the code for swiping images on next and previous UI button press.
this is my code

public GameObject[] gunSwipe; public int arrayIndexer;
public void BtnController(string name){

     if(name == "Next"){
         arrayIndexer++;
         for(int i = 0; i< gunSwipe.Length-1; i++){
             if(i== arrayIndexer){
                 gunSwipe[arrayIndexer].SetActive(true);
             }else{
                 gunSwipe[arrayIndexer].SetActive(false);
             }
         }

     }

II this is working for next button, but when i reverse it for previous button it does not work, arrayIndexer--; is working but it does not swipe the image