Flask can't see my virtual hosting's IP address

Question

I was trying to run my flask script with no debug on my domain (linux):

if __name__ == "__main__":
    app.run(debug=False, host="0.0.0.0")

but when started it said this:

* Running on all addresses (0.0.0.0)
 * Running on http://127.0.0.1:5000
 * Running on http://127.0.4.49:5000

and there wasn't my site. It basically doesn't see my ip address and doesn't count it at all when typing it into app.run(host) parameters. what should I do?

Typing virtual machine's actual ip address didn't work:

 * Serving Flask app 'main'
 * Debug mode: off
Cannot assign requested address