Upload excel file

[eluser]henrihnr[/eluser]
Dear CI users..

I need to upload an excel file, which is in 2003 or 2007 format..
with 2003 format it works fine but 2007 format always return error message 'The filetype you are attempting to upload is not allowed.'

here's the code

Code:

$config['upload_path'] = 'uploads/';
$config['allowed_types'] = 'xls|xlsx';
        
$this->load->library('upload', $config);
    
if ( ! $this->upload->do_upload())
{
   echo $this->upload->display_errors();
}

anyone help me, please..