Help VirtualChest

please im add plugin VirtualChest and recieve this problem!

[Server thread/CRITICAL]: Error: "Class 'pocketmine\permission\PermissionManager' not found" (EXCEPTION) in "VirtualChest-PMMP-master/src/kim/present/virtualchest/VirtualChest" at line 156
[22:28:26] [Server thread/DEBUG]: #0 src/pocketmine/plugin/PluginBase(102): kim\present\virtualchest\VirtualChest->onEnable()
[22:28:26] [Server thread/DEBUG]: #1 src/pocketmine/plugin/PluginManager(611): pocketmine\plugin\PluginBase->setEnabled(boolean 1)
[22:28:26] [Server thread/DEBUG]: #2 src/pocketmine/Server(1931): pocketmine\plugin\PluginManager->enablePlugin(kim\present\virtualchest\VirtualChest object)
[22:28:26] [Server thread/DEBUG]: #3 src/pocketmine/Server(1917): pocketmine\Server->enablePlugin(kim\present\virtualchest\VirtualChest object)
[22:28:26] [Server thread/DEBUG]: #4 src/pocketmine/Server(1711): pocketmine\Server->enablePlugins(integer 1)
[22:28:26] [Server thread/DEBUG]: #5 src/pocketmine/PocketMine(237): pocketmine\Server->__construct(BaseClassLoader object, pocketmine\utils\MainLogger object, string C:\BlackHatSociety\, string C:\BlackHatSociety\plugins\)
[22:28:26] [Server thread/DEBUG]: #6 C:/BlackHatSociety/PocketMine-MP.phar(1): require(string phar://C:/BlackHatSociety/PocketMine-MP.phar/src/pocketmine/PocketMine.php)

 

Have you tried contacting the plugins dev first?

 

I tried
the responsavel team seems to be inactive = (