Log collection REST API

I'm trying to fetch ScaleIO logs using the REST API. Here's what I did:

1. Login to user the Installation Manager API using :
   POST https:// /j_spring_security_check
   form_data:
   j_username=admin
   j_password=
   submit=Login
2. Submit request to the IM log collection API:
   POST to https:// /im/types/NodeInfo/instances/actions/collectLogs?copyRepositories=true&collectExceptionOnly=false&liteVersion=false
   Headers:
   Cookie: JSESSIONID:
   Accept: application/json
   Content-type: application/json

The collectLogs request returns a HTTP 400 – Bad Request response.

What am I missing?