Why Moodle themes are not displayed?

I have a problem with all non-standard themes in my Moodle instance (localhost, Mac OS X, MAMP): no non-standard theme is displayed in theme selection list. I have added three new themes: my own custom theme (kpzrs) and two downloaded custom themes (simple and essential). But there is only standard 'Clean' theme in selection list (screenshot: https://yadi.sk/i/BYEXiTOKX6eh8). As I've read in manuals, the problem may be caused by the wrong permissions for theme's folder. But all non-standard themes have same permissions with standard themes (screenshot: https://yadi.sk/i/dwXnzKXAX6fbT).