[5e Battlemaster] - doesn't seem to work

[geoidesic]

I created a new game, invited a player, assigned the 5E Roll20 Character Sheet, created a character for that player, dragged the token out onto the battle map, assigned it to the player, dragged some kobolds onto the map, added a turn for each token, then typed !combat start... and nothing happened. Then I cycle through the turns and... nothing happens.

What am I doing wrong?