error Undefined variable: Server

I'm trying to execute a function in another plugin but it tells me undefined variable server

code: 1

PHP:

public function PvP($player){

                   $plugin = $this->getServer()->getPluginManager();
         $formapi = $plugin->getPlugin("FormAPI");
         $form = $formapi->createSimpleForm(function (Player $event, array $args){
             $result = $args[0];
             $player = $event->getPlayer();
             if($result === null){
             }
             switch($result){
                 case 0:
        $this->gamesf($player);
                 return;

                 case 1:
        $Server->getInstance()->getPluginManager()->getPlugin("buhc")->app(); //function that I want to execute
                 return;

         }
         });
         $form->setTitle(TextFormat::WHITE . "--= " . TextFormat::BOLD . TextFormat::DARK_PURPLE . "Juegos" . TextFormat::RESET . TextFormat::WHITE . " =--");
         $name = $player->getName();
         $form->addButton("ATRAS");
         $form->addButton("BUHC");
         $form->sendToPlayer($player);
          }

Code: 2 error

PHP:

public static function app(Player $player){
        $this->arenaManager->addNewPlayerToQueue($player); //function that I want to execute
    }

Spoiler: Error

2018-01-10 [01:03:14] [Server thread/CRITICAL]: Could not pass event 'pocketmine\event\server\DataPacketReceiveEvent' to 'FormAPI v1.0.0': Undefined variable: Server on jojoe77777\FormAPI\FormAPI
2018-01-10 [01:03:14] [Server thread/CRITICAL]: ErrorException: "Undefined variable: Server" (EXCEPTION) in "CoreGames/src/YunoSiwa/CoreGames/Main" at line 124
2018-01-10 [01:03:14] [Server thread/DEBUG]: #0 CoreGames/src/YunoSiwa/CoreGames/Main(124): pocketmine\error_handler(integer 8, string Undefined variable: Server, string C:\Users\usuario\Desktop\VeryImportantPig\plugins\CoreGames\src\YunoSiwa\CoreGames\Main.php, integer 124, array Array())
2018-01-10 [01:03:14] [Server thread/DEBUG]: #1 FormAPI-master/src/jojoe77777/FormAPI/FormAPI(66): YunoSiwa\CoreGames\Main->YunoSiwa\CoreGames\{closure}(pocketmine\Player object, array Array())
2018-01-10 [01:03:14] [Server thread/DEBUG]: #2 src/pocketmine/plugin/MethodEventExecutor(38): jojoe77777\FormAPI\FormAPI->onPacketReceived(pocketmine\event\server\DataPacketReceiveEvent object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #3 src/pocketmine/plugin/RegisteredListener(98): pocketmine\plugin\MethodEventExecutor->execute(jojoe77777\FormAPI\FormAPI object, pocketmine\event\server\DataPacketReceiveEvent object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #4 src/pocketmine/plugin/PluginManager(721): pocketmine\plugin\RegisteredListener->callEvent(pocketmine\event\server\DataPacketReceiveEvent object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #5 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(91): pocketmine\plugin\PluginManager->callEvent(pocketmine\event\server\DataPacketReceiveEvent object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #6 src/pocketmine/network/mcpe/protocol/BatchPacket(115): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\ModalFormResponsePacket object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #7 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(92): pocketmine\network\mcpe\protocol\BatchPacket->handle(pocketmine\network\mcpe\PlayerNetworkSessionAdapter object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #8 src/pocketmine/Player(2998): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #9 src/pocketmine/network/mcpe/RakLibInterface(143): pocketmine\Player->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #10 vendor/pmmp/raklib/server/ServerHandler(99): pocketmine\network\mcpe\RakLibInterface->handleEncapsulated(string 192.168.1.68:43921, raklib\protocol\EncapsulatedPacket object, integer 0)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #11 src/pocketmine/network/mcpe/RakLibInterface(82): raklib\server\ServerHandler->handlePacket()
2018-01-10 [01:03:14] [Server thread/DEBUG]: #12 src/pocketmine/network/Network(89): pocketmine\network\mcpe\RakLibInterface->process()
2018-01-10 [01:03:14] [Server thread/DEBUG]: #13 src/pocketmine/Server(2522): pocketmine\network\Network->processInterfaces()
2018-01-10 [01:03:14] [Server thread/DEBUG]: #14 src/pocketmine/Server(2274): pocketmine\Server->tick()
2018-01-10 [01:03:14] [Server thread/DEBUG]: #15 src/pocketmine/Server(2149): pocketmine\Server->tickProcessor()
2018-01-10 [01:03:14] [Server thread/DEBUG]: #16 src/pocketmine/Server(1737): pocketmine\Server->start()
2018-01-10 [01:03:14] [Server thread/DEBUG]: #17 src/pocketmine/PocketMine(554): pocketmine\Server->__construct(BaseClassLoader object, pocketmine\utils\MainLogger object, string C:\Users\usuario\Desktop\VeryImportantPig\, string C:\Users\usuario\Desktop\VeryImportantPig\plugins\)
2018-01-10 [01:03:14] [Server thread/DEBUG]: #18 C:/Users/usuario/Desktop/VeryImportantPig/Phar.phar(1): require(string

 

Where Is Your $Server Variable?

PHP:

//example variable
$Server = $this->getServer();

 

Make sure to have the use pocketmine\Server; and also replace $Server->getInstance()->getPluginManager()->getPlugin("buhc")->app(); with $this->getServer()->getInstance()->getPluginManager()->getPlugin("buhc")->app();