using testfor in execute command failure

What I did: I used the command

execute @e[name="name"] ~ ~ ~ testfor @a[team=B]

What I expected to happen: It would output a redstone energy signal depending on the amount of players in that team around the entity.
What actually happened: It would only output because the testfor command succeeded, not because it had detected multiple players. It had not given a different redstone energy level (2 instead of 1).