scheduling an event is failing is 400 error

I am trying to create a scheduled event using oauth 2 API. I am not sure why the API is failing with 400 Bad Request error. Could you please help me to figure out the issue?

request url: https://api.calendly.com/invitees
request method: post

request headers included
authorization bearer <token>
content-type application/json

request payload

{
  'event_type': 'https://api.calendly.com/event_types/742a5393-093d-474b-abda-1ffdd446fb7e',
  'start_time': '2025-12-01T19:27:04.0000Z',
  'invitee': {
    'email': 'user_001@test.com',
    'name': 'Test User001',
    'first_name': 'Test', 
    'last_name': 'User001', 
    'timezone': 'America/Los_Angeles'
  },
  'location': {
    'kind': 'inbound_call'
  }
}

response code: 400

response payload:

{"title":"Invalid Argument","message":"The supplied parameters are invalid."}

reponse headers:
x-request-id: 5e18b628-eb03-4771-8f56-96f9341e5261