cannot sync ical

I still cannot sync ical between my 3 devices iMac, iPhone 4 and iPad 2. I can sync via icloud between my iMac and iPhone and Ipad but not vice-a-versa. Thus I can create an agenda item and delete it from my iMac and that will also br created/ deleted on the iPhone and iPad.

I have followed the apple troubleshooting instructions but that does not help. Troubleshooting iCloud Calendar.

Anyone know how to solve?