Displaying success message after form is submitted - php

Question

My form was working perfectly fine and displays the success message when the form is submitted. However, I just added a small piece of code and though the form submits, it doesn't display the success message anymore.
This is my code:
public function entrymarks()
{
$this->form_validation->set_error_delimiters('', '');
$this->form_validation->set_rules('exam_group_class_batch_exam_subject_id', 'Subject', 'required|trim|xss_clean');
if ($this->form_validation->run() == false) {
$data = array(
'exam_group_class_batch_exam_subject_id' => form_error('exam_group_class_batch_exam_subject_id'),
);
$array = array('status' => 0, 'error' => $data);
echo json_encode($array);
} else {
$exam_group_student_id = $this->input->post('exam_group_student_id');
$insert_array = array();
$update_array = array();
if (!empty($exam_group_student_id)) {
foreach ($exam_group_student_id as $exam_group_student_key => $exam_group_student_value) {
$attendance_post = $this->input->post('exam_group_student_attendance_' . $exam_group_student_value);
if (isset($attendance_post)) {
$attendance = $this->input->post('exam_group_student_attendance_' . $exam_group_student_value);
} else {
$attendance = "present";
}
$cal1 = $this->input->post('exam_group_student_ca1_' . $exam_group_student_value);
$cal2 = $this->input->post('exam_group_student_ca2_' . $exam_group_student_value);
$cal3 = $this->input->post('exam_group_student_ca3_' . $exam_group_student_value);
$cal4 = $this->input->post('exam_group_student_ca4_' . $exam_group_student_value);
$exam = $this->input->post('exam_group_student_exam_' . $exam_group_student_value);
$total = $cal1 + $cal2 + $cal3 + $cal4 + $exam;
if ($total > 0) { // This line may be the problem
$array = array(
'exam_group_class_batch_exam_subject_id' => $this->input->post('exam_group_class_batch_exam_subject_id'),
'exam_group_class_batch_exam_student_id' => $exam_group_student_value,
'attendence' => $attendance,
'get_ca1' => $cal1,
'get_ca2' => $cal2,
'get_ca3' => $cal3,
'get_ca4' => $cal4,
'get_exam' => $exam,
'get_tot_score' => $total,
'note' => $this->input->post('exam_group_student_note_' . $exam_group_student_value),
);
$insert_array[] = $array;
}
}
}
$this->examgroupstudent_model->add_result($insert_array);
$array = array('status' => '1', 'error' => '', 'message' => $this->lang->line('success_message'));
echo json_encode($array);
}
}
How do I get the success message to display again?