Assume that you set the system time zone of a device to UTC+8 or an earlier time zone such as UTC+9. In this situation, you cannot sign in to Microsoft Lync for Mac 2011 on the device. Additionally, if the device is deployed in an on-premises Lync Server 2010 or Lync Server 2013 environment, you may encounter the following issues:
The contact pictures that are stored in Active Directory Domain Service (AD DS) are not displayed in Lync for Mac 2011.
Your contact information in Address Book file is not synchronized to Lync Server 2010 or Lync Server 2013.
These issues occur because Lync for Mac 2011 calculates the expiration time of a web ticket based on an incorrect time zone. Therefore, when Lync for Mac 2011 tries to use the web ticket, the ticket is expired.
To resolve these issues, install the following hotfix:
2926055 Description of the Microsoft Lync for Mac 2011 14.0.7 hotfix