Hi,
Thank you for posting in Symantec community.
I would be glad to answer your query.
Do you see Enterprise Edition 12.1? & looking for Small Business Edition 12.1?
There are two editions.
1) 12.1 Enterprise Edition
2) 12.1 Small Business Edition
Upgrade from Enterprise Edition 11.x to Small Business Edition (SBE) 12.1 is not possible. Ideally you should have brought Enterprise Edition 12.1 only.
To install Small Business Edition need to uninstall existing SEP version first.
I would suggest to call license department, here you will find contact details:
Customer support assistance: http://www.symantec.com/support/assistance_care.jsp