404 Error when Testing Request class validation through Chrome Postman Extension

Below is my Controller Action method. You can see I passed a param of Request Class to validate before going to save the data in database

public function store(RoleRequest $request)
{
}

My Request class is below.

class RoleRequest extends Request
{
    private $Role;

    public function __construct(IRole $_role) {
        $this->Role = $_role;
    }        
    public function authorize()
    {
        return true;
    }    
    public function rules()
    {
        return [
            'Role' => 'required|max:20|min:4,
        ];
    }    
}

Above code works perfectly when I run it through web page(blade).

I created one more controller for API to Send save request. Below is the code

class RoleApiController extends Controller
{
    public function store(RoleRequest $request)
    {

    }
}

Issue comes, when I type just 1 char for role name and the Request class impose validation and I get 404 error This time I am sending request from Postman Extension in Chrome.

via Chebli Mohamed