Additional Drivers button disabled on Windows 2012 R2

Hello,

I'm trying to add 32 Bit Printer Drivers on a Windows 2012 R2 Print Server but when I opened Printer Properties/Sharing the Additional Drivers button is disabled. How do I enable the button and install additional drivers for 32 bit machines.

Printer : Xerox 5030 Work Center

I need to provide same server for 32 Bi and 64 Bit Clients on the same print server.

Thanks

RG