Problem Generating Embed URI using API

[frankya]

Hello Looker Devs,

We are trying to call lookers API  ​create_sso_embed_url to generate a url we can use with an iframe to embed in another app.We were able to get past the authentication error, but now we are getting a 404 ‘resource not found’. Any thoughts ? I have attached our postman response and request. thanks . ps i was not able to find this error listed in the api’s reference 

Request URL: https://domain.cloud.looker.com:443/api/3.1/embed/sso_url

Authorization Header: Bearer type token, must be generated using login api from api docs.

Request Body:

{

"target_url": "https://domain.cloud.looker.com/dashboards-next/15?Cusip=00036110",

"session_length": 86400,

"force_logout_login": true,

"external_user_id":"user-4",

"permissions":["access_data","see_looks", "explore"],

"models": ["Fixed_Income"]

}

Response: