iPhone Calendar Entries won't import/sync onto Macbook iCal

I thought that when I synced my iPhone to my iCal on my Macbook that this was a two-way street so that entries I put into my phone would be imported to my computer and entries I put on my computer will be imported to my phone. I need this to go both ways so I don't miss appointments! 😟 Can anyone help me with how to fix this problem? I don't want to replace everything on my iPhone with what's on my computer either. I know that's an option, but not what I'm looking to do. There are entries I add to my iPhone when I'm out and about and it doesn't help me when those don't later import to my computer. Thanks in advance!

P.S. I should add that I do not have iCloud. I upgraded my older macbook to snow leopard recently, but still no iCloud. I mention this because the other solutions for this issue I've seen on the forums all mention iCloud and that's not an option for me.