Can't connect to (our_hostname): IO::Socket::INET: connect: Unknown error at E:/OTRS/otrs//Kernel/System/CustomerAuth/LDAP.pm line 149.

This is our code:

#Enable LDAP authentication for Customers / Users
    $Self->{'Customer::AuthModule'} = 'Kernel::System::CustomerAuth::LDAP';
    $Self->{'Customer::AuthModule::LDAP::Host'} = 'our_hostname';
    $Self->{'Customer::AuthModule::LDAP::BaseDN'} = 'ou=users,dc=xxxxx,dc=com';   where xxxxx=our_domain
    $Self->{'Customer::AuthModule::LDAP::UID'} = 'sAMAccountName';

    #The following is valid but would only be necessary if the
    #anonymous user do NOT have permission to read from the LDAP tree
    $Self->{'Customer::AuthModule::LDAP::SearchUserDN'} = 'LDAP';
    $Self->{'Customer::AuthModule::LDAP::SearchUserPw'} = 'Help_Password';

    #CustomerUser
    #(customer user database backend and settings)
    $Self->{CustomerUser} = {
      Module => 'Kernel::System::CustomerUser::LDAP',
      Params => {
      Host => 'our_hostname',
      BaseDN => 'OU=users,DC=xxxxx,DC=com',      where xxxxx=ourdomain
      SSCOPE => 'sub',
      UserDN =>'LDAP',
      UserPw => 'Help_Password',
    },
    # customer unique id
    CustomerKey => 'sAMAccountName',
    # customer #
    CustomerID => 'mail',
    CustomerUserListFields => ['sAMAccountName', 'cn', 'mail'],
    CustomerUserSearchFields => ['sAMAccountName', 'cn', 'mail'],
    CustomerUserSearchPrefix => '',
    CustomerUserSearchSuffix => '*',
    CustomerUserSearchListLimit => 250,
    CustomerUserPostMasterSearchFields => ['mail'],
    CustomerUserNameFields => ['givenname', 'sn'],
    Map => [
      # note: Login, Email and CustomerID needed!
      # var, frontend, storage, shown, required, storage-type
      #[ 'UserSalutation', 'Title', 'title', 1, 0, 'var' ],
      [ 'UserFirstname', 'Firstname', 'givenname', 1, 1, 'var' ],
      [ 'UserLastname', 'Lastname', 'sn', 1, 1, 'var' ],
      [ 'UserLogin', 'Login', 'sAMAccountName', 1, 1, 'var' ],
      [ 'UserEmail', 'Email', 'mail', 1, 1, 'var' ],
      [ 'UserCustomerID', 'CustomerID', 'mail', 0, 1, 'var' ],
      [ 'UserPhone', 'Phone', 'telephonenumber', 1, 0, 'var' ],
      #[ 'UserAddress', 'Address', 'postaladdress', 1, 0, 'var' ],
      #[ 'UserComment', 'Comment', 'description', 1, 0, 'var' ],
    ],
  };
   
Please Help!

Thanks.