invalid serial index

[mordred]

recently i'm getting this message when I'm casting spell on combat.
I use this script for casting some spells:

sub Harm()
if UO.Count("0x1F38")>0 then
UO.Exec("usetype 0x1F38")
UO.Exec("waittargetlast")
else
UO.Print("No pergas PKT!!")
UO.Exec("cast Harm last")
end if
end sub

and the others spells are in the hoytkeys menu. if anyone knows what am I doing wrong please tell me

[SeeK-n-DeSTroY]

When you type UO.Exec("cast Harm last") Injection understand cast Harmlast.. but Harmlast does not exist.

I noticed that you use frequently UO.Exec.
This way Injection inits a new process and the problems are various.
Try this script:

sub Harm()
if UO.Count("0x1F38")>0 then
UO.useType("0x1F38")
UO.waitTargetLast
else
UO.Print("No pergas PKT!!")
UO.Cast("Harm","last")
end if
end sub

[Lord Ruslan Nightmare]

wrong!
You must call waittarget* BEFORE cast, use, or something else what requires target

[Yoko]

you must understand that Last in injection and Last Target in client is a different things. in injection LastTarget is ONLY that item you targeted by circle cursor in client. If you used macro Target Next you must use laststatus object pointer, e.g. uo.cast("Harm","laststatus")