CodeIgniter: error loading custom library - php

Question

I created a custom Library in CodeIgniter, and positioned it in application/libraries/VarMatrixSpecanimal.php
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class VarMatrixSpecanimal {
protected $variabiliMatrix;
public function __construct() {
$variabiliMatrix['cat']['no']=1;
$variabiliMatrix['dog']['a']=2;
$variabiliMatrix['bird']['b']=3;
}
public function get_matrix() {
return $this->variabiliMatrix;
}
}
?>
Then in one controller (application/controllers/certificate.php) method I added these two lines of code:
public function save1()
{
//..... some more code before
$this->load->library('VarMatrixSpecanimal');
$numerical_values = $this->varmatrixspecanimal->get_matrix();
//..... some more code after
But when I call save1 method, I get this error:
A PHP Error was encountered
Severity: Notice
Message: Undefined property: Certificate::$varmatrixspecanimal
Filename: controllers/certificate.php
Line Number: 139
I don't understand where I do wrong, please help me.
I checked also CodeIgniter help http://www.codeigniter.com/user_guide/general/creating_libraries.html but I was not able to get my error

Answer 1

Add get_instance() function in constructor in VarMatrixSpecanimal.php
public function __construct()
{
$this->variabiliMatrix =& get_instance();
}
After this load library on your controller
$this->load->library('varmatrixspecanimal');

Answer 2

I have experienced anything like this because I forgot this line of code:
parent::__construct
in my __construct or constructor.

Answer 3

Add include file with correct path at the top of program will solve this issue.
include "../../VarMatrixSpecanimal.php";

Answer 4

Try to change your constructor from this:
public function __construct() {
$variabiliMatrix['cat']['no']=1;
$variabiliMatrix['dog']['a']=2;
$variabiliMatrix['bird']['b']=3;
}
to this:
public function __construct() {
$this->variabiliMatrix['cat']['no']=1;
$this->variabiliMatrix['dog']['a']=2;
$this->variabiliMatrix['bird']['b']=3;
}
Also, when loading your library i think you don't need to uppercase any letters