API create new invoice response "Invalid value passed for contact_name"
I am getting the message when I post a new invoice
"Invalid value passed for contact_name"
Below is the json I am using for zoho books api invoice with post.
{
"customer_id": 606193000000060000,"reference_number": "Testing","invoice_number": "ATHTESTING","date": "2017-07-08","payment_terms": "15","due_date": "2017-07-20","discount": "210","line_items": [{"item_id": "606193000000058465"},{"item_id": "606193000000058465"},{"item_id": "606193000000058465"}]
}
This is a few more than minimum. The problem is the API Docs dont mention anything about contact_name.
It has contact_persons but that is optional it says.