Unique field validation issue in laravel

I'm trying to validate a unique entry in my laravel app

following is my validation array,

$website = $websiteModel->find($id);

        $this->validate($request, [
            'subDomainName' => ['required','regex:/^[A-Za-z0-9 ]+$/'],
            'subDomainSuffix' => ['required'], 
            'packageType' => ['required'],
            'themeid' => ['required'],
            'lang' => ['required'],
            'user' => ['required'],
            'domain' => [
                'required',
                'string',
                'min:2',
                'max:255',
                Rule::unique('apps')->ignore($website)
            ],
        ], $request->all());

My validation working properly BUT,

When i tried to enter a duplicate value for my domain field, It get validated properly but not showing the error message, saying sorry the name is already exists...

<input type="text" id="domain" class="form-control" name="domain" >
{!! $errors->first('domain', '<span class="help-block" role="alert">:message</span>') !!}

Here in this span it shows nothing but in the common error message area it shows sorry the form cannot be updated... So how can I validate the field properly and display the relevant error message

via Chebli Mohamed