Can't open calendar

When I try and open calendar I get the screen that looks like an open nook but then it immediately crashes. I have shut down calendar and then re booted the iPad by pressing home button and sleep button at the same time but the same problem reoccurs.

I have also tired installing the new software update but it keeps saying to try again later as I am not connected to the Internet . However , I definitely am connected.

Please can some one help

Gillie