Fulfilment API Documentation Missing

Hello,

I’m having issues registering a fulfilment through the REST api.

Going off the example request I get the following:

Request:

https://xxxx.myshopify.com/admin/api/2021-10/fulfillments.json

{“fulfillment”:{“message”:“Your order was sent”,“tracking_info”:{“number”:“4202397092”,“url”:“https://tools.usps.com/go/TrackConfirmAction?tRef=fullpage&tLc=2&text28777=&tLabels=4202397092”,“Company”:“USPS Consolidator”},“line_items_by_fulfillment_order”:[{“fulfillment_order_id”:4376324538612}]}}

Response:

{“errors”:“Not Found”}

I’m not too sure whether this is the correct method, as the documentation doesn’t seem to be complete. When you click ‘show properties’ only notify_customer is displayed

Is there any ideas as to what could be going wrong?