Why can't I build factional units?

[Hybr1d]

I'm currently playing a Romani campaign and I can only build factional units on 3 of my cities on the Italian peninsula ( out of like 6 or cities ). And I look in the city and it already has a barracks, yet I can't build any Roman units in it. Any help?

[MarcusAureliusAntoninus]

You can only recruit Roman units in the starting cities (+Segesta) until the Polybian Era.

[desert]

Yes, but there are more than 3 starting cities.

[Hax]

You haven't built level 4 governments in there, right?

[Maion Maroneios]

Actually, it's training not building. And it has to do with the government types you have there. Only lvl1 (for sure) and lvl2 government buildings give you the ability of building factional MICs which, in turn, allow you to train factional troops like Principes and Triarii.

Maion