Function in pocketmine not producing results :setCount()

Code:

                $e->getPlayer()->setHealth($e->getPlayer()->getHealth()+1);
                Server::getInstance()->broadcastMessage($e->getPlayer()->getInventory()->getItemInHand()->getCount()." gold");
                $e->getPlayer()->getInventory()->getItemInHand()->setCount($e->getPlayer()->getInventory()->getItemInHand()->getCount()-1);
                Server::getInstance()->broadcastMessage($e->getPlayer()->getInventory()->getItemInHand()->getCount()." gold");

Is this function not available or am i using it wrong?

What is happening? The value doesn't change?

Yeah, the player is holding 11 gold,
it should set the 11 to 11-1 but instead it is still 11.

Maybe the inventory is changed but not updating...

Right. $player->getInventory()->sendContents($player) try again.