Own class library Codeigniter

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PHP

CodeIgniter

Hello! I try make own library class and call it from other class.
I created file SimpleImage.php and put it at directory application/libraries/
The file contents class:

<?
class SimpleImage {
 
   var $image;
   var $image_type;
 
   function load($filename) {
 
      $image_info = getimagesize($filename);
      $this->image_type = $image_info[2];
      if( $this->image_type == IMAGETYPE_JPEG ) {
 
         $this->image = imagecreatefromjpeg($filename);
      } elseif( $this->image_type == IMAGETYPE_GIF ) {
 
         $this->image = imagecreatefromgif($filename);
      } elseif( $this->image_type == IMAGETYPE_PNG ) {
 
         $this->image = imagecreatefrompng($filename);
      }
   }
}
?>

I have also other library class Myupload.php with class:

<?
class Myupload {

    function UploadFiles($options)
    {
   $CI = & get_instance();
   $CI->load->library('SimpleImage');
   $CI->SimpleImage->load($path.$info_file['file_name']); // 44 line
   $CI->SimpleImage->resize(200,200);
   $CI->SimpleImage->save($path.$info_file['raw_name'].'_thumb.'.$info_file['file_ext']);
}

}
?>

But it gives me error:

Severity: Notice

Message: Undefined property: Apartaments::$SimpleImage

Filename: libraries/Myupload.php

Line Number: 44

What is wrong?