Bandwidth Optimization options locked

I’m running Drupal 8.1.5 site. At /admin/config/development/performance the “Bandwidth Optimization” settings for “Aggregate CSS Files” and “Aggregate Javascript files” are disabled, so I cannot change their state. Can you help me, please.

http://es.tinypic.com/view.php?pic=280jhvt&s=9#.V_5gE-jhCUk

my config:

http://es.tinypic.com/view.php?pic=2hxste&s=9#.V_5gZOjhCUk

Best Regards

Drupal version: 


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