Quote Originally Posted by Marquis of Roland
It's probably bugged. I believe you only need an Imperial Palace IN Italy somewhere and it has to be after 220B.C. I got mine at around 215, was kinda disappointed because I didn't get to use the pre-reform troops as much (I never got to build any triarii EVER).

Reinstall it and see if it works then?
Triarii are kinda overrated anyway. Thanks (or, no thanks, depending on who you ask) to a bug, getting an Imperial Palace will allow you to build Praetorian Cohorts, which are obviously far better than any pre-marion infantry. They are the only troops which can testudo before Marius comes around.