Hi,
You can convert that client from unmanaged to managed client if want to do so.
How to change a Symantec Endpoint Protection client from unmanaged to managed
http://www.symantec.com/business/support/index?page=content&id=TECH102322&locale=en_US
I hope you are trying to deploy 32 bit package on 32bit operating systems and 64bit package on 64bit operating systems.
Create 32bit group and move all 32bit clients into the same group. Try to deploy 32bit package and check if it works.