https.request ignoring rejectUnauthorized

I'm trying to connect to a remote server using nodejs 0.12, and i keep getting the response SELF_SIGNED_CERT_IN_CHAIN. I have looked at similar questions 1 2 but somehow their solutions don't work on my server.

I am connecting to a test environment outside of my control setted up with a self signed certificate. This is my request:

var https = require("https");
var fs = require('fs');

start();

function start()
{
    var listadebancos = 
    {
        language:"es",
        command:"GET_BANKS_LIST",

        merchant:
        {
            apiLogin:"11959c415b33d0c",
            apiKey:"6u39nqhq8ftd0hlvnjfs66eh8c",
        },

        test:true,
        bankListInformation:
        {
            paymentMethod:"PSE",
            paymentCountry:"CO"

        }
    };

    var listadebancosString = JSON.stringify(listadebancos);

    var headers = 
    {
        'Content-Type': 'application/json',
        'Content-Length': listadebancosString.length
    };

        var options= {
            host: 'stg.api.payulatam.com',
            rejectUnauthorized: false,
            agent:false,
            path: '/payments-api/4.0/service.cgi',
            method: 'POST',
            cert: fs.readFileSync('./stg.gateway.payulatam.crt'),

        }

        process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";

        var req= https.request(options, funcionRespuesta);
        req.write(listadebancosString); 
        req.end();



        function funcionRespuesta(res) 
        {   console.log(res);
        }

    }

Am i missing something obvious?