I cannot install antivirus software

I have got myself Symantec Anti-Virus updated version i.e., 8.0. All I want is to install it in my personal computer and set my computer system so that it acts as an Anti-Virus Server platform. But during installation process it results in an error message saying the following string.
“The feature that you are trying to use is on a network resource that is unavailable” How could I proceed?

Error:
Symantec AntiVirus
Error 1714 The older version of Symantec AntiVirus cannot be removed.Contact your technical support group.
