Revieve error {"code":1002,"message":"Statement of Accounts does not exist."} when creating invoice in Books from Creator.

Revieve error {"code":1002,"message":"Statement of Accounts does not exist."} when creating invoice in Books from Creator.

I receive the following error message when trying to create an invoice in Zoho Books from Creator:
  1. {"code":1002,"message":"Statement of Accounts does not exist."}

Here is the statement i'm using to create the invoice:
  1. response = zoho.books.createRecord("Invoices","6699999999",values);
Here are the contents of the 'values' variable being inserted into the zoho.books.createRecord statement:

Values{"customer_id":62944600000011xxxx,"reference_number":"afa","date":"03-Apr-2020","line_items":[{"item_id":"125789400000155xxxx","name":"210XGD","quantity":1,"description":"blah blah blah"},{"item_id":"125789400000155xxxx","name":"211AGD","quantity":1,"description":"blah blah blah"},{"item_id":"125789400000155xxxx","name":"212AGD","quantity":1,"description":"Blah blah Blah"},{"item_id":"125789400000155xxxx","name":"213AGD","quantity":1,"description":"blah blah blah"}]}

Please let me know what I'm missing.
Perry