At some point in time, after upgrading Lync 2013 client to Skype for Business on a workstation, I noticed the Calendar icon disappear (version 15.0.4727.1001).  Then I noticed on a different workstation where Skype was NOT loaded (version 15.0.4701.1000) the icon was gone as well.  After installing Skype for Business updates, with it remaining Skype for Business, the "new" calendar icon is present and functional.  How do I get that icon back on clients Lync 2013, without it disappearing.  This is happening on both Windows 7 and 8.1 workstations.  We are running Lync Server (standalone) 2013.