I run bitcoind default wallet path.but ı request getballance from nodejs api return;

UnhandledPromiseRejectionWarning: RpcError: Requested wallet does not exist or is not

loaded

I use createwallet rpc method, I created testwallet after I use loadwallet "testwallet" rpc method after that I use listwallets rpc method return json;

[ "", "testwallet" ]

but when I run bitcoind as -walletdir = ... / testwallet, it says that this walet is used.

I want to connect with testnete walet. bitcoin core version 0.18.0 help me please.