As a reminder. You are posting in the Express forums. If you are a current Standard Edition customer, you should be working with support.
5.1.x (released January 2013) ended support on January of this year. Commercial customers with extended support have support for 2 more years.
RHEL 6.7 (released on 7/22/2015) and derivatives became officially supported with Centrify 5.3 released in December 2015.
Express users get community-based support in this forum, however you must be within 5.3.x.