Shopify order Fulfillments api endpoint not working.

[afifaakhtar]

Hi

I am creating a Shopify private app in which I am changing the fulfillment status of an order through API. now I am using the API endpoint

 /admin/api/2021-10/orders/orderID/fulfillments.json

I can access all the others from the API credentials but for this only endpoint it is 

{"errors":"[API] Invalid API key or access token (unrecognized login or wrong password)"}

 I am a new Shopify developer. I saw one person saying change access mode but I don't know how can I do it.

I am using Shopify API key that starts with shppa_