Laravel - 干预/图像错误：NotWrittableException无法将图像数据写入路径

I tried to use Intervention/image for my Laravel project, and I have a problem. I have this line of code:

Image::make($avatar)->fit(150,150)->save(public_path() . DIRECTORY_SEPARATOR . 'images' . DIRECTORY_SEPARATOR . 'avatar', "{$this->id}.jpg");

And I have this error :

NotWrittableException Can't write image data to path F:\wamp\www\ecommerce\public\images\avatar

I put the directory separator because otherwise I had this url "F:\wamp\www\ecommerce\public/images/avatar"

I don't know what to do for solve this problem. I'm on Laravel5 in local with WampServer.

I have all the rights on my folder, and if you want, I have my laravel.log file here: https://drive.google.com/file/d/0Bw8CroQWVzRNY0lRSjdCc2dXT1E/view

If you have an idea, that will help me a lot. Thank you in advance!