Problem with assist focus macro

[Nacnik]

/assist focus
/castsequence reset=combat/target Mondfeuer, Insektenschwarm, Zorn, Sternenfeuer, Sternensog, Zorn, Zorn, Zorn, Zorn, Zorn, Zorn

I tried this but there seems to be a little issue still. Sometimes it works but sometimes he just spams Moonfire.
Has the focus person to be in sight to target his target correctly?

Thanks again!