Minecraft testfor not me

As per the Minecraft Wiki Commands page, the syntax of the /testfor command is either of:

/testfor <playername>
/testfor <selector>

So, e.g., a command block that fires the command /testfor notch, with a redstone comparator attached to it, would output a signal from the comparator, assuming that Notch is playing on that server.

Using the Command Block selectors syntax lets you do things like /testfor @a[r=3], which will cause the comparator to emit a signal strength equal to the number of players within three meters. Or /testfor @a[m=2], which would cause the comparator to emit a signal strength equal to the number of Creative Mode players currently on the server.

In order to increment by 1 anytime a player dies, the objective must be type deathCount. Something like this would work:

/scoreboard objectives add deaths deathCount Deaths

If you're making dummy objectives, you're using a similar command except with "dummy" in place of "deathCount." A dummy objective can only be changed with the following commands:

/scoreboard players add (player) (objective) (value)

/scoreboard players remove (player) (objective) (value), and

/scoreboard players set (player) (objective) (value)