In my computer I have upgrade operating system to Mac OS X lion. I am facing problem while synchronizing calendar with the iCal. Whenever I try to put calendar entry in the iCal at that time I get error. After that when I select Revert to Server option at that time it ask me for ignore or go Offline. I don’t know whether problem is on my system or problem is with the iCloud. What should I do to solve this problem?