Mirage Source

For I = 1 To MAX_MAP_NPCS
Map.Npc(I) = cmbNpc(I - 1).ListIndex
Next I

MAX_NPCS needs to be stored as an integer if you want the value to be more than 255.

' ::::::::::::::::::::::
' :: Npc spawn packet ::
' ::::::::::::::::::::::
If LCase(Parse(0)) = "spawnnpc" Then
n = Val(Parse(1))

MapNpc(n).Num = Val(Parse(2)) 'runtime error 6 : overflow
MapNpc(n).x = Val(Parse(3))
MapNpc(n).y = Val(Parse(4))
MapNpc(n).Dir = Val(Parse(5))

' Client use only
MapNpc(n).XOffset = 0
MapNpc(n).YOffset = 0
MapNpc(n).Moving = 0
Exit Sub
End If

It would appear that you need to change the num variable to an integer in the mapnpc rec.