Update Unit (setUnit)

I want to update the unit number(pcs, pks, etc...) on my quotation line,

 

            $enhedensnr=$orderData->UnitHandle->Number;
            echo "<h1>Enhedens nummer: ".$enhedensnr."</h1>";
            $opdater_linje_enhed = $client->QuotationLine_SetUnit(array('quotationLineHandle'=>$opret_linje, 'valueHandle' => $enhedensnr))->QuotationLine_SetUnitResponse;

Whats wrong with this one ?

I can echo the value via PHP, but i cant update it on e-conomic