Laravel5: NotFoundHttpException in RouteCollection.php line 161

I've clone a repository from github,but getting error in routing for admin, the same code is running well on another developer machine, we both are using Window 8.

We are using Auth Middleware to validate user for logged in but when I tried to access the admin http://ift.tt/1691lrz I am getting this error

NotFoundHttpException in RouteCollection.php line 161

But frontend works fine. I've tried to execute following command in terminal but same issue after that

composer install
php artisan clear--compiled

Also I checked the registered routs & its showing in terminal by using command

php artisan route:list

Here are my route.php

Route::get('/', function () {
    return view('welcome');
});


// Logging in and out
get('/login', 'Auth\AuthController@getLogin');
post('/login', 'Auth\AuthController@postLogin');
get('/logout', 'Auth\AuthController@getLogout');

Route::group(['namespace' => 'Admin','prefix' => 'admin','middleware' => 'auth',], function () {

    resource('/', 'AdminController');

    resource('/countries', 'CountryController');

});

.htaccess file code

<IfModule mod_rewrite.c>
    <IfModule mod_negotiation.c>
        Options -MultiViews
    </IfModule>

    RewriteEngine On

    # Redirect Trailing Slashes If Not A Folder...
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)/$ /$1 [L,R=301]

    # Handle Front Controller...
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^ index.php [L]
</IfModule>

via Chebli Mohamed