diff --git a/user_manual/pim/calendar.rst b/user_manual/pim/calendar.rst
index a2ac02576..5f4098359 100644
--- a/user_manual/pim/calendar.rst
+++ b/user_manual/pim/calendar.rst
@@ -35,6 +35,8 @@ The Calendar app contains the following fields and controls:
   controls include sharing, obtaining an external URL link to the calendar, an
   export function, an edit function, and a delete (trash) button.
 
+  .. note:: Some Ad-Block plugins hide the "Share" button for calendars. If the "Share" button is missing, try disabling your Ad-Block plugin or add a whitelist-entry for your OwnCloud instance.
+
 - Calendar Settings -- Provides access to the calendar-specific settings.  These
   settings include the calendar timezone selection, time format selection, week
   start day, cache setting, primary CalDAV address, and iOS/OS X CalDAV address
@@ -318,4 +320,4 @@ can also set the timezone manually in the personal settings.
 
 .. |download| image:: ../images/download.png
 .. |caldavlink| image:: ../images/calendar_caldav_icon.png
-.. |gear| image:: ../images/gear.png
\ No newline at end of file
+.. |gear| image:: ../images/gear.png