C# Container subtypename is prohibited

Hello,
I would like to ask a error: subtypename is prohibited

My code is:

if (argument == "kontener1")
{
szoveges2.WritePublicText("", false);
szoveges2.WritePublicText("\nKonténer1:", true);
IMyInventory kontainer1inventory = kontener1.GetInventory(0);
kontainer1ItemsList = kontainer1inventory.GetItems();
var kontener1tomeg = kontener1.GetInventory(0).CurrentMass;
foreach (IMyInventoryItem elem in kontainer1ItemsList)
{
szoveges2.WritePublicText("\n" +...

C# Container subtypename is prohibited