Calendar won't let me add new events on my iPhone Suddenly my iPhone won't let me add new events to my calendar. In the upper right hand corner of the 'month' calendar there are 3 symbols.


A rectangular box with 2 lines underneath. 
A magnify glass. 
A '+'
The first two are red and active
The third one is gray and inactive. 


I've read solutions to problems from others, but nothing has helped. 
I also have and iPad, and the calendar on it works fine. I have compared settings on both products, and they seem to be set the same way.
I had the same problem, went into the calendar, tapped on "Calendars" in the bottom center, here there were two calendars listed - holidays, and birthdays.  I pulled down on these items (like scrolling, the screen refreshed then showed 5 calendars.  From some reason I-cloud was not selected, I selected this and all the calendars listed became active.

I went back to the calendar view (by month) and am now able to add events.

BTW, none of the other options I have tried worked, only this method.  Under general settings both my iCloud and Yahoo calendars were active, but under the actual program they were not.  Don't waste your time in the general settings change it from the program.