Q: My calendar not syncing with iPhone 6s using iTunes on a Mac

I have always been able to add events on my iphone and MacBookPro and sync them manually through iTunes.  Now that I have the new iPhone 6s, I am unable to get them to sync.  I have all the proper settings checked on the iphone when I plug it into itunes.  Has anyone had this issue?  How do I solve it.  I don't want to use the cloud, I prefer to sync using iTunes.