can not running

[hidexir]

(~/.go/src/github.com/jun06t/grpc-sample/bidirectional-streaming)
❯ go run server/main.go

(~/.go/src/github.com/jun06t/grpc-sample/bidirectional-streaming)
❯ go run client/main.go [master] U
2018/09/22 01:00:38 send message: tokyo
2018/09/22 01:00:38 send message: 001
2018/09/22 01:00:38 send message: Japan
2018/09/22 01:00:38 rpc error: code = Unavailable desc = transport is closing
exit status 1

please tell me