Not applicable to ESX version below 4.1 Patch 3

I have removed the vShield endpoint app and now when I try to re-add it I get the message:

"Not applicable to ESX version below 4.1 Patch 3"

I'm running ESX 5.0. I have found this kb article but it made no difference:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2007082

Anyone come across this issue?