iCal couldn’t connect to p07-caldav.icloud.com

I run iCal on my MacBook Pro, iPhone 4S and iPad2 through iCloud

I am able to add events on the iPad and iPhone which update automatically on iCloud and the MacBook - the way it should work ... BUT when I add an event on the MacBook it does not update iCloud or the iPad/iPhone.

The error message is "server is not responding" "iCal couldn’t connect to p07-caldav.icloud.com" "check internet connection. My internet is working correctly.

Can someone please help me. The MacBook has all my work appointments & they are not updating & I am missing/double booking myself.

Thanks