SonataAdmin Install issue - symfony

Question

I trying to install SonataAdmin on my Symfony Project but at the end of the part-2 of the documention when i'm trying to go on "http://localhost:8000/admin/" I have a error : "You have requested a non-existent service "admin.category" in . (which is being imported from "C:\wamp64\www\Sonata/app/config\routing.yml"). Make sure there is a loader supporting the "sonata_admin" type."
I have no idea why, i give give my all my parameters code maybe it's can help you to understand my problem.
parameters:
#parameter_name: value
services:
# default configuration for services in *this* file
_defaults:
# automatically injects dependencies in your services
autowire: true
# automatically registers your services as commands, event subscribers, etc.
autoconfigure: true
# this means you cannot fetch services directly from the container via $container->get()
# if you need to do this, you can override this setting on individual services
public: false
admin.category:
class: AppBundle\Admin\CategoryAdmin
arguments: [~, AppBundle\Entity\Category, ~]
tags:
- { name: sonata.admin, manager_type: orm, label: Category }
# makes classes in src/AppBundle available to be used as services
# this creates a service per class whose id is the fully-qualified class name
AppBundle\:
resource: '../../src/AppBundle/*'
# you can exclude directories or files
# but if a service is unused, it's removed anyway
exclude: '../../src/AppBundle/{Entity,Repository,Tests}'
# controllers are imported separately to make sure they're public
# and have a tag that allows actions to type-hint services
AppBundle\Controller\:
resource: '../../src/AppBundle/Controller'
public: true
tags: ['controller.service_arguments']
# add more services, or override services that need manual wiring
# AppBundle\Service\ExampleService:
# arguments:
# $someArgument: 'some_value'
`
The indentation is going wrong i add you a picture of this file. Service code

Answer 1

The sonata admin services must be public. In your config, you have default as public: false and that is why you get this error.
So you have 2 options:
Specify public: true for your admin service (in your example file)
Or the better way: create a new services file (eg admin.yml) where you dont use these defaults (the _defaults key with public: false). Public is true by default, so you don't have to specify that by _defaults. In this case you must import your new file in config.yml to work:
Top of app/config.yml
imports:
- { resource: parameters.yml }
- { resource: security.yml }
- { resource: services.yml }
- { resource: admin.yml }
app/admin.yml content:
services:
admin.category:
class: AppBundle\Admin\CategoryAdmin
arguments: [~, AppBundle\Entity\Category, ~]
tags:
- { name: sonata.admin, manager_type: orm, label: Category }

Answer 2

I think you did a mistake by writing your category.admin service in: Sonata/app/config/routing.yml,
instead of Sonata/src/YourAdminBundle/Resources/config/services.yml

Answer 3

Run this command on terminal. Because You might have missed installing
php composer.phar require sonata-project/doctrine-orm-admin-bundle
After This Add this code below to your AppKernel.php
// app/AppKernel.php
public function registerBundles()
{
return array(
// ...
// set up basic sonata requirements
// ...
new Sonata\DoctrineORMAdminBundle\SonataDoctrineORMAdminBundle(),
// ...
);
}