Hello,
What version of Liveupdate Administrator (LUA) are you running?
Make sure you are running the Latest version of LUA 2.3.2, Check this Article -
LiveUpdate Administrator (LUA) version 2.3.2 is now available
Also, Make sure the SEPM and LUA are not on the same server.
LiveUpdate Administrator 2.x and Symantec Endpoint Protection Manager on the same computer
http://www.symantec.com/docs/TECH105076
and
Follow the Steps provided in the Article below:
Endpoint Protection 12.1 Clients fail to apply Virus and Spyware Protection definitions from LiveUpdate Administrator 2.x
http://www.symantec.com/docs/TECH196873
Secondly, check this Article on -
LiveUpdate Administrator 2.x Server Connection Recommendations
Hope that helps!!