Socket.io + NodeJS doesn't work on Heroku

I am doing an API and it's on Heroku. But I am having some problems with the socket.io only on the heroku side, when I test it in local everything goes fine. The API is completely independent of the frontend, so they are in a different domains (and a different hosts). The problem is that on production, I don't get succeed in connect the sockets...I am doing an API and it's on Heroku. But I am