يظهر خطأ 500 internal server error من أجل ملف .htaccess

السلام عليكم

يظهر خطأ 

وبعد الاطلاع على ملف الأخطاء في الخادم، وجدت هذه العبارة:

/.htaccess: RewriteEngine must be On or Off, referer: http://mujtama.madarisweb.com/

وهذا هو الكود للملف:

AddDefaultCharset utf-8

RewriteEngine on

RewriteRule ^c([0-9]+) cats.php?id=$1 [L]
RewriteRule ^u-(.*) users.php?name=$1 [L]
RewriteRule ^i([0-9]+) items.php?id=$1 [L]
RewriteRule ^massages-(.*) msgs.php?by_user=$1 [L]
RewriteRule ^sitemap.xml sitemap.php [L]
RewriteRule ^api.xml api.php [L]
RewriteRule ^login log.php [L]
RewriteRule ^forgot-password forgot_pass.php [L]
RewriteRule ^signup reg.php [L]
RewriteRule ^cats cats.php [L]
RewriteRule ^massages msgs.php [L]
RewriteRule ^users users.php [L]
RewriteRule ^about about.php [L]
RewriteRule ^search search.php [L]
RewriteRule ^notifications notify.php [L]
RewriteRule ^faq faq.php [L]
RewriteRule ^privacy privacy.php [L]
RewriteRule ^terms terms.php [L]
RewriteRule ^contact contact.php [L]

ولا أدري أين المشكلة؟