Have you tried exiting out of the calendar app? Double tap the menu button to bring up the task manager. Tap and hold the calendar icon till a "-" sign appears on the icon's top left. Tap the "-" sign to shut the app, then tap anywhere on the main screen to close the task manager.
I did some searches and the main issue I found was the calendar not being turned on in iCloud. The first 5 gigs is free on iCloud so it will not cost you anything to set up iCloud and turn the calendar on to see if it works.
Sorry it took so long to reply. As a school teacher I find that my personal stuff gets put o. The back burner. That being said, I went to settings and clicked on I cloud and put in my I'd and password an it keeps telling me that it cannot connect to server meanwhile I have a strong signal strength. Any ideas as to why this is happening?