Laravel 5 validate error message not showing

Sorry, i am a beginner for laravel 5, I try to validate register form but it not showing error message. Any idea why errors are not displaying. Please help.

thank you so much.

Here are my code

View

                        <form role="form" method="post" action="">
                      <div class="form-group">
                        <label for="name">Full Name</label>
                        <input  type="text" name="fullname" class="form-control" id="fullname" value="" placeholder="Enter your fullname">
                        @if ($errors->has('fullname'))
                            <span class="help-block"></span>
                        @endif
                      </div>
                        <div class="form-group">
                            <label for="email" class="control-label">Your email address</label>
                            <input type="text" name="email" class="form-control" id="email" value="" placeholder="Enter your email">
                            @if ($errors->has('email'))
                                <span class="help-block"></span>
                            @endif
                        </div>
                        <div class="form-group">
                            <label for="password" class="control-label">Choose a password</label>
                            <input type="password" name="password" class="form-control" id="password" placeholder="Enter your password">
                            @if ($errors->has('password'))
                                <span class="help-block"></span>
                            @endif
                        </div>
                        <div class="form-group">
                            <label class="control-label">Confirm Password</label>
                            <input type="password" class="form-control" name="password_confirmation" placeholder="Re-Enter your password">

                            @if ($errors->has('password_confirmation'))
                                <span class="help-block">
                                    <strong></strong>
                                </span>
                            @endif
                        </div>
                        <input type="hidden" name="activated" value="0">
                        <input type="hidden" name="_token" value="">
                        <button type="submit" class="btn btn-warning btn-sm">Submit</button>
                        <button type="reset" class="btn btn-default btn-sm">Reset</button>
                    </form>

Controller

public function postRegister(Request $request) {

    $this->validate($request, [
        'email' => 'required|email|max:255',
        'password'  =>'required|alphaNum|Between:4,8|Confirmed',
        'password_confirmation'=>'required|alphaNum|Between:4,8',
        'fullname' => 'required|max:255',
        'activated' => 'required',
    ]);

    Admin::create([
        'email' => $request->input('email'),
        'password' => $request->input('password'),
        'fullname' => $request->input('fullname'),
        'activated' => $request->input('activated')
    ]);

    return redirect('backoffice/register')->with('info', 'register successfully!');

}

Route

Route::get('backoffice/register', 'AdminAuthController@getRegister');
Route::post('/backoffice/register', 'AdminAuthController@postRegister');

via Chebli Mohamed