ADOdb活动记录关系设置

我有2个表，user &country 注意:表名为单数

ADOdb_Active_Record::TableKeyBelongsTo(
    'user', // child table name
    'id', // child primary key
    'country', // parent table name
    'country_id', // child foreign key
    'id' // parent primary key
);
class User_Model extends ADOdb_Active_Record {
    var $_table = 'user';
    ...
}
ADOdb_Active_Record::TableKeyHasMany(
    'country', // parent table name
    'id', // parent primary key
    'user', // child table name
    'country_id' // child foreign key
);
class Country_Model extends ADOdb_Active_Record {
    var $_table = 'country';
    ...
}
$user = new User_Model();
$user->load('id=1');

但是这个错误显示

1146: Table 'happylucky.countries' doesn't exist
                           ADOConnection._Execute(SHOW COLUMNS FROM `countries`, false) % line 1017, file: adodb.inc.php
                        ADOConnection.Execute(SHOW COLUMNS FROM `countries`) % line  410, file: adodb-mysql.inc.php
                     ADODB_mysql.MetaColumns(countries) % line  390, file: adodb-active-record.inc.php
                  ADODB_Active_Record.UpdateActiveTable() % line  239, file: adodb-active-record.inc.php
               ADODB_Active_Record.belongsTo(country, country_id, id, ADODB_Active_Record) % line  263, file: adodb-active-record.inc.php
ADODB_Active_Record::UpdateActiveTable: Invalid table name: countries
Fatal error: Class 'User' not found in /home/user/public_html/project/application/controllers/welcome.php on line 23

我的关系设置错了吗?或者表名必须是复数?