服务端代码：namespace Home\Controller;
use Think\Controller\HproseController;
class ServerController extends HproseController{
    public function test1(){
        return 'test1';
    }
    public function test2(){
        return 'test2';
    }
}客户端代码：namespace Home\Controller;
use Think\Controller;
class IndexController extends Controller {
    public function index(){
        vendor('Hprose.HproseHttpClient');
        $client = new \HproseHttpClient('http://localhost/App/index.php/Home/Server');
        $result = $client->test1();
        dump($result);
    }
}报错：
Warning: mkdir() [function.mkdir]: Invalid argument in D:\MyWWW\phpStudy\WWW\App\ThinkPHP\Library\Think\Log\Driver\File.class.php on line 39
错误位置
FILE: D:\MyWWW\phpStudy\WWW\App\ThinkPHP\Library\Vendor\Hprose\HproseClient.php 　LINE: 94
TRACE
#0 D:\MyWWW\phpStudy\WWW\App\ThinkPHP\Library\Vendor\Hprose\HproseClient.php(113): HproseClient->invoke('test1', Array)
#1 D:\MyWWW\phpStudy\WWW\App\Application\Home\Controller\IndexController.class.php(8): HproseClient->__call('test1', Array)
#2 D:\MyWWW\phpStudy\WWW\App\Application\Home\Controller\IndexController.class.php(8): HproseHttpClient->test1()
#3 [internal function]: Home\Controller\IndexController->index()
#4 D:\MyWWW\phpStudy\WWW\App\ThinkPHP\Library\Think\App.class.php(162): ReflectionMethod->invoke(object(Home\Controller\IndexController))
#5 D:\MyWWW\phpStudy\WWW\App\ThinkPHP\Library\Think\App.class.php(200): Think\App::exec()
#6 D:\MyWWW\phpStudy\WWW\App\ThinkPHP\Library\Think\Think.class.php(120): Think\App::run()
#7 D:\MyWWW\phpStudy\WWW\App\ThinkPHP\ThinkPHP.php(96): Think\Think::start()
#8 D:\MyWWW\phpStudy\WWW\App\index.php(24): require('D:\MyWWW\phpStu...')
#9 {main}

请问是什么原因？