custom library not load

hi
i create custom library for payment gateway but when load in my controller  show me blank page.

function  invoice(){
           
           
           
            
           $invoice_id=$this->input->post('invoice_id');
           $amount=$this->input->post('amount');
           $Description=$this->input->post('Description');
           $MerchantID='xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx';
           $CallbackURL='url';
           $Mobile='09126015062';
           $Email='[email protected]';
         
           
           $this->load->library('mylibrary');
           $this->mylibrary->request($MerchantID,$amount,$Description,$CallbackURL,$Mobile,$Email);
           
    
     $student_profile         = $this->db->get_where('student', array(
         'student_id' => $this->session->userdata('student_id')
        ))->row();
        $student_id              = $student_profile->student_id;
        $page_data['invoices']   = $this->db->get_where('invoice', array(
            'student_id' => $student_id
        ))->result_array();
        $page_data['page_name']  = 'mypal';
        $page_data['page_title'] = get_phrase('manage_invoice/payment');
        $this->load->view('index', $page_data);
        
    }      

i found when load  library this problem happens.

please help me what wrong in this code