add TAG, shortcut/command ?

Hello,

ever since i can remember I've been able to use "option, cmd, T" to add a tag for a file, (on my macbook)

with my mac mini, the command/option doesn't seem to be available, is it something i have to activate?

screen shot pictured below for both OS's.

many thanks in advance,
stuart

 

thank you, i couldn't quite get it to work - but going back, how comes their would be this function on a macbook pro, but not a mac mini do you think ?