I can use the sql server management studio to open a sqlserver 2000 database,

but I can not open the same database in a php page using the same user and password.

what is the problem?

if(!$dbSource->open("192.168.4.241:1433","sa","sa","NorthWind"))
{
    echo  "Fail to open the sql server 2000 database";
}

-----------------------

  function open($db_server, $db_user, $db_password, $db_name) 
  {

    $this->conn = mssql_connect($db_server, $db_user, $db_password);
    if(!$this->conn)
    {
        return false;
    }
    @mssql_select_db($db_name, $this->conn);
    return true;
  }