Problem with KeyUp and arrows

Question

I have one problem. I want to use the right and left arrows to scroll through the images, and I did it perfectly. The right arrow goes forward and the left arrow goes backward. And when I press the right arrow, then it's like pressing the left arrow, and again when I press the right arrow again, only then do the pictures scroll, and so every time, so I have to double-click the right arrow to scroll through the pictures, so does the left. Mostly you will notice that when I click the arrow, that "button" is in blue which means like I pressed it but I didn't.
Here is the video: 668392526

        private void nxt_KeyUp(object sender, KeyEventArgs e)///Next image
        {
            if(e.KeyCode == Keys.Right)
            {
                try
                {

                    next++;
                    slike.Image = listaSlika.Images[next];


                }
                catch (Exception ex)
                {

                    MessageBox.Show("Nema vise opcija za naprijed!");
                }
                if (next > 3)
                {
                    next = 3;
                }
            }
        }

        private void prev_KeyUp(object sender, KeyEventArgs e)//Previous image
        {
            if (e.KeyCode == Keys.Left)
            {
                try
                {
                    next--;
                    slike.Image = listaSlika.Images[next];

                }
                catch (Exception ex)
                {
                    MessageBox.Show("Ne mozes nazad!");
                }
                if (next < 0)
                {
                    next = -1;
                }
            }
        }

Answer 1

@Jack J Jun @Castorix31 @Rool0507

Now I put the code under the switch, and I merged these two buttons into one event and still have
I still have a problem with the button, when I press the left arrow the first time, it looks like I clicked the right button, but I didn't, and the second time I press the left click, then it's fine, but that's how it goes. So I just have one more problem left, you can see it better in the video.

private void nxt_KeyUp(object sender, KeyEventArgs e)  
                {  
                    switch(e.KeyCode)  
                    {   
                     case Keys.Left:  
                        try  
                         {  
                    
                    next--;  
                    slike.Image = listaSlika.Images[next];  
              
                }  
                catch (Exception ex)  
                {  
                    MessageBox.Show("Ne mozes nazad!");  
                }  
                if (next < 0)  
                {  
                    next = -1;  
                }  
                break;  
                    case Keys.Right:  
                        try  
                {  
      
                    next++;  
                    slike.Image = listaSlika.Images[next];  
           
      
                }  
                catch (Exception ex)  
                {  
                    MessageBox.Show("Nema vise opcija za naprijed!");  
                }  
                if (next > 3)  
                {  
                    next = 3;  
                }  
                break;  
            }  
        }