Problem with sources in FPDF

I am trying to generate a PDF, if I created everything in the same directory there is no problem, the problem comes when I call the function that will generate this doc.

  

Warning: include (font / helveticab.php): failed to open stream: No such file or directory in /Applications/XAMPP/xamppfiles/lib/php/fpdf.php on line 1145

     

Warning: include (): Failed opening 'font / helveticab.php' for inclusion   (include_path = '.: / Applications / XAMPP / xamppfiles / lib / php') in   /Applications/XAMPP/xamppfiles/lib/php/fpdf.php on line 1145 FPDF   error: Could not include font definition file

I get the feeling that calling it from another file and folder does not find that doc.

define('FPDF_FONTPATH','font/');
require_once('fpdf.php');
require_once('include/crud_usuario.php');
require_once('include/class_usuario.php');


$crud = new CrudUsuario;
$usuario = new Usuario;
$usuario = $crud->obtenerUsuario($_GET['id_usuario']);

And the function,

public function matricula(){
    $pdf = new PDF;
    $usuario = new Usuario;
    /*antes de AddPage para que se apliquen los cambios*/
    $pdf->SetTitle('Matricula - MC');
    $pdf->SetLeftMargin(25);
    $pdf->SetRightMargin(25);
    /**/
    $pdf->AddPage();
    $y_axis_initial = 25;
    $pdf->SetFont('Arial','B',12);
    $pdf->Ln(10);
    $pdf->InfoFicha($usuario);
    /*Lo guardamos el PDF con dni de la persona*/
    return $pdf->Output('matricula-'.$usuario->getDni().'.pdf','I');
}