Why is the add event plus sigh gray instead of red on my iPhone 5s?

[iMore Question]

I am unable to add an event on my iPhone 5s calendar because the plus sign is gray (inactive) instead of red.

 

[Peligro911]

I am unable to add an event on my iPhone 5s calendar because the plus sign is gray (inactive) instead of red.

check your account that are associated with your calendars