SkDragon problem

[Famix]

Hello!
I have a problem with skdragon.
code:

    loop {circle.list::*}:
        if {circle.loc.%loop-value%} exists:
            set {_loc} to loop-value
            drawHalo particle "redstone", center at {_loc} , id "circle.all.%arg-1%", rainbowMode true, solid true, density 10, visibleRange 10

i need the particle to be on that place.

Erorr:
The expressin "argument" can only be used within a command