Effective January 2015, Google discontinued the free Google sync product for all users. This only affects users who sync their Google calendar to Outlook or other 3rd party services. Google is requiring users to now pay for the sync tool through their Google Apps for business subscription. This service is $5 per month or $50 per year and is ordered through Google.
Google Apps for Business -
We also have found a lower cost tool for $19.95. We have not thoroughly tested this application out, but it allows for two-way sync between Outlook and your Google Calendar. This tool does not support Mac versions of Outlook.