Rest Epcior Erp.BO.ARInvoiceSvc

Hi, everybody i have a trouble with Rest

I try to create a Credit Memo and return this exception:

"HttpStatus": 400,
  "ReasonPhrase": "REST API Exception",
  "ErrorMessage": "Customer is required.",
  "ErrorType": "Ice.Common.BusinessObjectException",
  "ErrorDetails": [
      "Message": "Customer is required.",
      "Type": "Error",
      "Table": "InvcHead",
      "Program": "Epicor.RESTApi.dll",
      "Method": "ThrowUpdateExtException",
      "ColumnNumber": 17,
      "LineNumber": 40

this is my Json:
  "Company": "EPIC07",
  "OpenInvoice": true,
  "CustNum": 39,
  "ClosedDate": "2020-04-01",
  "CreditMemo": true,
  "GroupID": "Test3",
    "InvoiceRef": 10017, 
    "InvoiceNum": 0, 
"TranDocTypeID": "CreditMemo",
"PMUID": 2,
"CustomerCustID": "HG",
"BTCustomerName": "Hector Garcia",
"SoldToCustomerName": "Hector Garcia",
"CustomerName": "Hector Garcia",
"FiscalPeriod": 4

someone can help me? there are CustNum and CustomerCustID.

thanks and Regards.

“SoldToCustNum”: 17,

thnak you for your Answer.

that’s solution!