Topic: Devise ldap authenticatable returns 401 error

I am making some application in rails in which user needs to be log-in first to see the content, I used devise and ldap_devise_authenticatable to make user log-in through existing LDAP account but when i tried to log in with my account into my application then log-in failure occurs(401 error unauthorized) even though I already have account on ldap.

I used the following tutorial … nd_27.html

And following is the screenshot of my ldap server page
PunBB bbcode test

I know the problem is in my ldap configuration file. How can i configure it properly so that my application send correct string to ldap server like in above screenshot

Code of my ldap.yml is as follows:

authorizations: &AUTHORIZATIONS
  group_base: ou=groups,dc=test,dc=com
    - cn=admins,ou=groups,dc=test,dc=com
    - cn=users,ou=groups,dc=test,dc=com
    - [