Can't use @p[type=Player] {SelectedItemSlot:0} as a target

Please provide the entire command issued.

I'm using this sequence

Legends
C = Redstone Clock
CMD = Command Block
Comp = Comparator

C - CMD - Comp - CMD

1st CMD =

testfor @p {SelectedItemSlot:0}

2nd CMD =

clear @p {SelectedItemSlot:0}

Comment: I'm trying to do this on my server to make a "Slot to Command Feature"

Please if i'm wrong could you post the right tag?

please reply mods. THanks

In terms of the issue title, you need to use @e. Still waiting on a way to check for NBT tags more easily. I wish they got merged with the brackets somehow, so they wouldn't be an additional portion of each command. Some commands have too many parameters, especially the new fill and clone functions, so somehow merging NBT with the bracket section makes more sense than figuring out where to put it separately.

well i'm looking forward for the right argument.

Fixed in 14w11b

Why would you need to use @p[type=Player]?