Trying to use suitetalk rest services to create a sales order... Getting

{
  "type": "<https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.1>",
  "title": "Bad Request",
  "status": 400,
  "o:errorDetails": [
    {
      "detail": "Error while accessing a resource. Field must contain a value.",
      "o:errorCode": "USER_ERROR"
    }
  ]
}

Any tips to figure out what Field its complaining about? I've tried going through and setting fields one at a time, but am striking out.