can't redirecting after clicking submit button - php

Question

I'm trying to upload a edited csv file, but after submission it do not redirect
with valid message. Actually if any error in the edited csv file it should give the error msg, otherwise success msg.
I want to upload the mark sheet of a particular subject, if the entered mark is not in numeric or it is exceeding the maximum mark valid messages will be displayed and redirect back to my view page.
function import_academic_excel()
{
$optional_index = 0;
if ($this->input->post('submit'))
{
$config['upload_path'] = './application/temp_upload/';
$config['allowed_types'] = 'csv';
$this->load->library('upload', $config);
if (!$this->upload->do_upload('userfile'))
{
$data = array('error' => $this->upload->display_errors());
$this->session->set_flashdata('msg_excel','Choose a .csv file to upload.');
redirect(base_url().'import_evaluation_sheet');
}
else
{
$count_numeric = 0;
$count_maximum = 0;
foreach($result as $field)
{
if($standard == 11 || $standard == 12)
{
if($evaluation_name == 'ta1' || $evaluation_name == 'ta2' || $evaluation_name == 'ta3')
{
if($subject_name == 'physics' || $subject_name == 'chemistry' || $subject_name == 'computer_science')
{
$theory_name=$subject_name.'_theory';
$practical_name=$subject_name.'_practical';
if($field[$theory_name] == '' )
{
$field[$theory_name]= 0;
}
if($field[$practical_name] == '' )
{
$field[$practical_name]= 0;
}
if($field[$theory_name] != 'ab')
{
if(!is_numeric($field[$theory_name]))
{
$count_numeric = $count_numeric + 1;
}
if($field[$theory_name] > $theory_mark)
{
$count_maximum = $count_maximum + 1;
}
}
}
}
}
}
}
if($count_numeric > 0)
{
$this->session->set_flashdata('msg_excel','Please check the marks entered in the file, some marks are not numeric.');
redirect(base_url().'import_evaluation_sheet');
}
if($count_maximum > 0)
{
$this->session->set_flashdata('msg_excel','Please check the marks entered in the file, some marks exceeds the maximum marks.');
redirect(base_url().'import_evaluation_sheet');
}
$update_result= $this->data->update_chapter($result,$subject_name,$evaluation_name,$optional_index,$standard,$tool_id);
$this->session->set_flashdata('msg_excel_success','Updated data successfully');
redirect(base_url().'import_evaluation_sheet');
}
}
The loops are working, but it can't enter to the last two if loops.
If I am entering valid csv file it will reflect in the data, but success msg can't displayed.