Scaling up Zeebe broker is not working

Hello, I am using Camunda 8.6 Self-managed with ONE Zeebe broker with ONE partition and ONE replication factor.
Now trying to scale the broker count to 2. Following below documentation.

I am able to scale new broker in the cluster. But when I try to send request to gateway (after port forwarding) to incorporate newly created broker, with below command

curl --request POST 'http://localhost:9600/actuator/cluster/brokers' \
-H 'Content-Type: application/json' \
-d '["0", "1", ]'

getting error

<!doctype html><html lang="en"><head><title>HTTP Status 404 – Not Found</title><style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status 404 – Not Found</h1></body></html>

Can anyone help?