Outlook 2013 and Win 8.1

Hi

I am not able to install the EV 10.0.4 plugin on my 8.1 machine with outlook 2013.

The same MSI installs fine on Win 7 Outlook 2010.

When i double click the MSI on win 8.1 i get:

"You cannot install the Symantec Enterprise Vault Outlook Add-In 10.0.4.1333 by launching the MSI file directory. You must launch setup.exe."

I have logged on with my account that has full domain access and is also within the local admin group on the laptop to be sure.

Thanks