invalid_grant - The provided authorization grant is invalid, expired, revoked, does not match the redirection URI used in the authorization request, or was issued to another client

[fs-arman]

Hi guys,
I tried to integrate the Google SSO Login in my rails app.
However, I tried to test it using Postman but return this error invalid_grant which I think return 400 Bad Request.

Below are the details of my parameters:
client_id/client_secret is the value from the doorkeeper oath_applications.
grant_type must be assertion
assertion is the access token return from Google Oauth, see screenshot below:

Any idea on how to resolved this issue? Thanks