Error While Trying To Generate Fedex Label Through API

When trying to generate a FedEx label through API for a sandbox account.
I get error “The remote server returned an error: (500) Internal Server Error.”

I am using endpoint “https://apiverson.ordoro.com/order/M-20191119-104909/label/fedex

passing the following json file

{“shipper_id”:209403,
“packages”:[{“box_shape”:“YOUR_PACKAGING”,“length”:8,“height”:6,“width”:4,“declared_value”:10.0,“dry_ice_weight”:0.0,“weight”:1.0}],
“recipient_address_is_residential”:false,
“delivery_confirmation”:“NO_SIGNATURE_REQUIRED”,
“shipping_method”:“FEDEX_GROUND”}

looks like a duplicate of Sandbox Shipper FedEx