What version did you upgrade from? What features are you trying to install on these servers?
Can you post the SEP_INST.log?
From start - run - %temp%\SEP_INST.log, search for Return Value 3 and post the 10 lines above the return value 3.
I am including the following article for your reference.
Installation and Migration Documents for Symantec Endpoint Protection 12.1 -
http://www.symantec.com/business/support/index?page=content&id=TECH163707&actp=search&viewlocale=en_US&searchid=1310411230555
Moving this thread to the Endpoint Protection forum.