Need help related to my codeigniter wallpaper script

Hello!

A new unknown for me.

When I try to add a wallpaper to favorites, returns me this error: "Wallpaper hash doesn't exists."

I think I managed to find where's the problem, but I don't know how to solve it.

There are 2 php files that are involved here:

1st is named wall_model.php

PHP Code:

class Wall_model extends WS_model
{
    public function getWallpaperByHASH($hash)
    {
        $this->wallpaperTemplate();
        $this->db->where('w.wallpaper_hash', $hash);
        return $this->row();
    }
} 


2nd

PHP Code:

  $hash = $this->input->post('hash');
        $this->load->model('wall_model');
        $wallpaper = $this->wall_model->getWallpaperByHASH($hash); // if i replace here "$hash" with the number of the hash wallpaper the favorite was successful registered.
//i think the hash is not loaded, that is why the error message. Can someone tell me if the code from "wall_model.php" is right? 


Thank you!

Check the $this->input->post('hash'); value