iPhone 4 Calendar won't sync to Macbook iCal

EDIT: gonna repost elsewhere, as I'm getting no response here.
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I often add events to my Calendar in my iPhone, while I'm out and about. I want these events to sync back to my Macbook. iCal syncs events in my Macbook to my iPhone, but not the other way around.

I don't recall being asked to choose between merging or replacing when setting up my iPhone, but according to http://support.apple.com/kb/ht1386:


"The first time you sync your device, you are asked if you want to merge data, replace data on the device, or replace the data on your computer. When you choose to merge information, any differences between the data will be mingled together. If you choose to replace information, information from either the computer or device will overwrite the information on the other. These options can not be undone. After that, anytime you connect your device to your computer, iTunes opens and syncs with your device according to the settings in iTunes."

I want to know if there's any way to do what I want to do. Wasn't quite sure where to post this...