Error Undefined type 'use\...\'

[thedeceiver3112]

I am having problems after using it
use PhpOffice\PhpPresentation\Shape\Chart\Type\BarClustered;
use PhpOffice\PhpPresentation\Shape\Chart\Type\BarStacked;
in the code I write:
$chart = new BarClustered();
$series = new BarSeries();
it says 'Undefined type 'PhpOffice\PhpPresentation\Shape\Chart\BarSeries'.
please help me.