You can train more troops at a time by building armories, or more armories. Also upgrade your armories. The number of troops you can train with just a barracks is minimal. You also need to keep an eye on your Squad Size, which will increase with every Squad size upgrade you do. The number reflected in your barracks, is the number of squads you have.
For example, say you can train 10 troops, but your squad size is a 100. Your increase shown in your barracks will be 10/100 = 0.1. Anything less than 0.1 won’t even show up.
If you absolutely get nothing and you do have a few armories, best to contact Support so they can check what is going on in your city.