Child theme does not appear in theme selection

I’m trying to add a child theme to my wordpress installation. The theme the child should be based upon a theme called “nostalgia-landing” which is installed and works properly. I created a new folder called “nostalgia-custom” and added the the style.css with the following content:

/*
Theme Name: Nostalgia Custom
Description: Nostalgia Custom is a responsive WordPress landing page.
Author: QuanticaLabs and Christoph Halang
Author URI: http://themeforest.net/user/QuanticaLabs?ref=QuanticaLabs
License: GNU General Public License version 3.0
License URI: http://www.gnu.org/licenses/gpl-3.0.html
Version: 2.0.2
Template: nostalgia-landing
*/
@import url("../nostalgia-landing/style.css");

However, the theme selection in admin panel does not show my child theme and says “You only have one theme installed right now.”. This is not true since there are the default themes. When I delete the child theme folder the default themes appear again in the selection.

Did I miss anything? Any ideas guys?

Regards,

Chris

Problem solved: My child themes folder and the enclosed files had permission 750 instead of 644 set. Changed the permission and everything is working!