Codeigniter photo thumb create and upload

it gives blank screen :/ it uploads first image, thats fine. than it call _create_thumbnail and it gives blank screen at line "$this->image_lib->resize()" :/

any idea what can be the problem?

Thanks!!

/**
* ==================================================================
* Upload photo
*
* Thumb = 210px – 160px
* Original = 500px – 385px
*
*/

function img_upload() 
{
    $config['upload_path'] = 'uploads/';
    $config['allowed_types'] = 'gif|jpg|jpeg|png';
    $config['max_size'] = '1000';
    $config['max_width'] = '1920';
    $config['max_height'] = '1280';     
    $config['width'] = 500;
    $config['height'] = 385;                

    $this->load->library('upload', $config);

    if(!$this->upload->do_upload()) echo $this->upload->display_errors();
    else {

        $fInfo = $this->upload->data();
        $this->_create_thumbnail($fInfo['file_name']);

        $data['uploadInfo'] = $fInfo;
        $data['thumbnail_name'] = $fInfo['raw_name'] . '_thumb' . $fInfo['file_ext'];

        // set view
        $this->load->view('upload_success', $data); 
    }
}

function _create_thumbnail($fileName) 
{
    $config['image_library'] = 'gd2';
    $config['source_image'] = 'uploads/' . $fileName;   
    $config['create_thumb'] = TRUE;
    $config['maintain_ratio'] = TRUE;
    $config['width'] = 210;
    $config['height'] = 160;

    $this->load->library('image_lib', $config);
    if(!$this->image_lib->resize()) echo $this->image_lib->display_errors();

}