Validation Error: Member must satisfy enum value set: [LTL, SP]

[var-grvr]

When trying for PutTransportDetailsRequest, I receive the following error for ShimentType:

sp_api.base.exceptions.SellingApiBadRequestException: [{'code': 'InvalidInput', 'message': "1 validation error detected: Value '' at 'shipmentType' failed to satisfy constraint: Member must satisfy enum value set: [LTL, SP]", 'details': ''}]. Here is the body of the request:

{ "IsPartnered": True, "TransportDetails": { "PartneredSmallParcelData": { "PackageList": [{ "Dimensions": { "Length": 1, "Width": 1, "Height": 1, "Unit": "centimeters" }, "Weight": { "Value": 1, "Unit": "kilograms", }, "CarrierName": "ATS", }], "CarrierName": "ATS" }, }, "ShipmentType": "SP", }

What could be the issue here?