Macbook stealing iCal entries

Grrrrrr. I am getting seriously frustrated.

I need to sync my Macbook and iphone calendars. I need all entries on both devices. More often than not, I add the entry on my iphone. However, whenever I sync with my Macbook, the calendar is wiped clean from my iPhone. I have tried every permutation of checking boxes in iTunes or in iCal, but nothing works.

Please help!!!