SleekXMPP proxy issue

I am using SleekXMPP to integrate a chat bot with Facebook. When I am not behind a proxy, I get the expected behavior. But when I am behind a proxy, the connection is not established. I took a look at the documentation and found that I should include this part:

    sleekxmpp.use_proxy = True
    sleekxmpp.proxy_config = {
        'host': '10.3.100.207',
        'port': 8080,
    }

This gives me this final code:

addr = ('chat.facebook.com', 5222)
ipaddr = ('209.85.175.125',5222)

chatbot = sleekxmpp.ClientXMPP(jid,password)
sleekxmpp.use_proxy = True
sleekxmpp.proxy_config = {
    'host': '10.3.100.207',
    'port': 8080,
}

But it does not connect to the server. Anyone could help?

Copyright Notice：Content Author:「Aakash Anuj」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/27204614/sleekxmpp-proxy-issue