plz help with this

hi all

i got this error when i try to login
error number: 256
Unknown column '' in 'where clause'
page:login.php?
file: include/dbconnection.php
line number: 26
sql: select * from `members` where ``='ahmed' and ``='123456'
----------------------------------------------------------------

here is my table dump:
--

-- Table structure for table `members`

--
CREATE TABLE `members` (

`id` int(10) NOT NULL auto_increment,

`username` varchar(100) NOT NULL default '',

`password` varchar(10) NOT NULL default '',

`group_id` int(2) NOT NULL default '1',

`active` enum('0','1') NOT NULL default '1',

PRIMARY KEY (`id`),

UNIQUE KEY `username` (`username`)

) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=6 ;
--

-- Dumping data for table `members`

--
INSERT INTO `members` (`id`, `username`, `password`, `group_id`, `active`) VALUES

(1, 'ahmed', '123456', 0, '1');
-------------------------------------------------------------

the key column in phprunner is (id)

and it works fine on my local apche server
i got this error only when puplished the mysql db is ok
so what's the problem

thanks,

ahmed