Getting permission issue in chats api

I have made an application which fetches the chats info to build an analytics on the no of messages send and received.

The user authorizing application has super admin permissions.

Steps:

• Fetch all chats by restapi/v1.0/glip/chats
• Fetch all messages for individual chats by: restapi/v1.0/glip/chats/chatid/posts

But while fetching one chat's post I get this message:

{
    "errors": [
        {
            "errorCode": "CHT-012",
            "message": "The requester must be team member."
        }
    ]
}

Why am I getting this error ? Are there any limitations in a way that could restrict super admin to access all the endpoints(including chat posts) ?