Laravel 4.2落后于ELB - Sessions无效

I'm running Laravel 4.2 with database session storage. My application is running behind a Load Balancer.

When only one instance is running, my application works fine. Then if i enable a second instance my application stops working.

My application adds a session to the database on almost every pageload, and i can't write/read sessions (and can't login).

Here is my session config

return array(

    'driver' => 'database',

    'lifetime' => 1440,

    'expire_on_close' => false,

    'files' => storage_path().'/sessions',

    'connection' => "mysql",

    'table' => 'sessions',

    'lottery' => array(2, 100),

    'cookie' => 'ycrm_session',

    'path' => '/',

    'domain' =>  null,

    'secure' =>  false,

);

My sessions table looks like this

Have anybody experied that issue before?