upload createPackage

Hi! I have been trying to upload multiple documents with a post request to '/api/packages' (the sandbox) url and getting getting the error indicating the number of documents sent in the payload is different from what I attached, Could have a look at the code and let me know, what I am missing?

var httpReq = require('superagent');
var _ = require('lodash');

var createPackageReq = httpReq
                                    .post(config.esignature.host + '/packages')
                                    .set('Content-type', 'multipart/form-data')
                                    .set