I am unable to synchronize my computer iCal with iCloud.

I have a MacBook Pro laptop, a MacPro and an iPhone 5. I have an iCloud account activated on computers and iPhone. I wish to make iCloud the default Calendar, so that any entries on laptop or on iPhone can be synchronized. I have not been able to get iCal on iCloud to respond or synchronize. Any entries made on laptop iCal do not appear on iCloud. The iPhone calendar also remains blank and does not record any entries made on laptop. In other words, none of the devices will communicate with each other or with the Cloud. I have searched Apple help pages and completed the setup instructions and trouble shooting questions which are relevant, with no success.

Can anyone give me some help? Thanks,