Why am I unable to add events to my iPhone calendar?

[iMore Question]

IPhone calendar

I just added ICloud for Outlook to my computer to sync calendars but now I am unable to add any events to my IPhone calendar

 

[Ledsteplin]

IPhone calendar

Which Calendar are you trying to add an event to? iCloud or Outlook? For the stock calendar, go to iCloud in settings and toggle calendar on.