exporters kafka with sasl get error

[jack161641]

Error: cannot build pipelines: cannot build builtExporters: error creating kafka exporter: kafka: client has run out of available brokers to talk to (Is your cluster reachable?)
2021/06/15 17:13:39 application run finished with error: cannot build pipelines: cannot build builtExporters: error creating kafka exporter: kafka: client has run out of available brokers to talk to (Is your cluster reachable?)

configfile below:
kafka:
protocol_version: 2.2.0
brokers:
- 10.2.103.187:9094
- 10.2.103.185:9094
- 10.2.103.186:9094
topic: otlp_spans
auth:
sasl:
username: kafka_user
password: xxxxx
mechanism: PLAIN

[jack161641]

use kafka without sasl is normal