Testfor team score not working

I'm developing a Minecraft mini-game and I want to execute a command when a team reach 0 points.

I've created a dummy objective:

/scoreboard objective add health dummy Health

And 3 teams:

/scoreboard teams add A-team teama
/scoreboard teams add B-team teamb
/scoreboard teams add C-team teamc

All teams start with 1000 points and depending what they do their points will be decreased, I want to execute a command when one team reachs 0 points. I'm using this but it doesn't work:

/testfor @a[team=A-team, score_health_min=0]

• I'm using Minecraft 1.9.1

Thanks in advance and sorry for my bad English.