Outlook not synching to iCloud anymore

The iCloud program I use in the Windows 7 control panel no longer synchronizes the Outlook Calendar with iCloud. I'm not sure what I've done to make it stop working, but I used to synchronize the two through iTunes where my phone was connected to my PC via a USB cable. I'm not sure, but then I think I clicked "Mail, Contacts, Calendars, and Tasks". However, I think that the contacts are syncing correctly, and it's just the calendars that aren't. Any ideas?