TI-API: API v2 Error: TI-API-00221 "No API Endpoint Found"

Hi team,

Our customer MEIKO (sold to 184740) tried to create a test order in sandbox for the first time, but they got below error.

            "Code": "TI-API-00221",

            "Message": "No API Endpoint Found"

Below is the data that they sent.

Could you please check why this error happened and how they can place a test order?

{
"order":{
"customerPurchaseOrderNumber":"MKEP2402-1-0370",
"shipToAccountNumber":"184737",
"endCustomerNumber":"1014110",
"endCustomerCompanyName":"",
"lineItems":[
{
"customerLineItemNumber":"1",
"tiPartNumber":"TRS3232EQPWRQ1",
"customerPartNumber":"GXE-007039-001-00",
"customerAnticipatedUnitPrice":0.391,
"customerCurrencyCode":"USD",
"schedules":[
{
"requestedQuantity":2000,
"requestedDeliveryDate":"2024-05-30"
}
]
}
]
}
}