iphone calendar to outlook sync problems

You may have selected the wrong default calendar on your phone. Check Settings>Mail,Contacts,Calendars>scroll down to the Calendar section and tap Default Calendar. Here be sure you have selected your Outlook calendar as your default, and not, for example, the calendar under On My iPhone. If you make a change to this setting, add a new event to your iPhone calendar and sync your phone to see if it transfers to Outlook.

You could try resetting your sync history as described here: http://support.apple.com/kb/HT1692. Another alternative would be to enable iCloud syncing if you have Outlook 2007 or 2010 and Vista SP2 or Windows 7. This will show you how to set it up on your computer: http://www.apple.com/icloud/setup/pc.html.

I had this issue a couple of times and the solution for me was very simple.

1. Locate the .ost file on your PC.

C:\Documents and Settings\[USERID]\Local Settings\Application Data\Microsoft\Outlook

Note you must have hidden files/folders enabled to see this path.

2. Make sure Outlook is not open

3. Rename the outlook.ost file to something like outlok.ost.old

4. relaunch Outlook

5. Launch itunes and re-sync