Login/Register not returning field values

[froot]

if($user->isLoggedin() && !$input->get('profile') && !$input->get('logout')) {
echo '<h2>'.__('Mein Profil').'</h2>';
echo '<p><strong>'.$user->fields[130].': </strong>' . '<span>'.$user->givenname.'</span></p>';
echo '<p><strong>'.$user->fields[131].': </strong>' . '<span>'.$user->lastname.'</span></p>';
echo '<p><strong>'.$user->fields[92].': </strong>' . '<span>'.$user->email.'</span></p>';
echo '<p><strong>'.$user->fields[171].': </strong>' . '<span>'.$user->units_balance.'</span></p>';
}

I don't know why none of the values don't return anything (in the span tags). Also, the ->fields[] API is not very elegant either.