Unreachable, msg: Authentication failure

This is my first time, and I am facing this issue.

I have used ansible_ssh_pass, and ansible_ssh_user also.

But this message is coming,

luvpreet@DHARI-Inspiron-3542:/etc/ansible$ sudo ansible -m ping all
vogo-alpha.cloudapp.net | UNREACHABLE! => {
“changed”: false,
“msg”: “Authentication failure.”,
“unreachable”: true
}

This is my file,
[webservers]
vogo-alpha.cloudapp.net ansible_ssh_pass=pass ansible_ssh_user=user

i can login via simple SSH.
I need to know why is this problem coming in the way ? WHat is the reason and a little hint about the solution ?

You need to run ansible with -vvvv to get more information about the reason.