Check if he below helps
Export client install package from 12.1 SEPM hangs at "Retrieving the package data from the management server"
http://www.symantec.com/business/support/index?page=content&id=TECH182408
https://www-secure.symantec.com/connect/forums/export-package-sepm-121-not-working#comment-6712961
https://www-secure.symantec.com/connect/forums/unable-export-package#comment-6390471
http://www.symantec.com/business/support/index?page=content&id=TECH102215
hope this helps