how to use KafkaJSONParser in scheduler?

I am trying to send messages from Kafka to Vertica flex table using KafkaJSONParser. 

However JSON formatted message does not load into table as JSON format.

This is my vkconfig topic command using KafkaJSONParser:

./vkconfig topic --edit --conf config.properties --target flextest1.kafka --rejection-table flextest1.kafka_rej --config-schema flextest1 --topic flextest1 --parser KafkaJSONParser

When I editted vkconfig topic, it is not updated in the table:

kafka=> select * from flextest1.kafka_targets;
target_schema | target_table | enabled | parser | rejection_table | parser_parameters | load_method | target_columns
---------------+--------------+---------+-------------+---------------------+-------------------+-------------+----------------
flextest1 | kafka | t | KafkaParser | flextest1.kafka_rej | | TRICKLE |
(1 row)

I even tried to change parser value manually to KafkaJSONParser, I am unable to parse as JSON formatted.

JSON formatted message I tried to send from Kafka:

{"mac": "f0:cb:d1:5b:b8:0f","ipAddress": "10.255.220.12"}

The message goes to __raw__ column as it is, but not JSON formatted.