Well, if I had to guess, here is a tip from the docs which might explain your problem:
To create lightning:
Add the objects
to the scene that you want the lightning to extend between.
Select the objects
you want the lightning to extend between.
By default, lightning will be created between all the selected objects
. If you want to change the Lightning Creation Controls, see Setting lightning creation controls. The order of selection determines the direction of the lightning, depending on the Creation Option you selected.
Notice a trend?
In order for lighning to be positioned with any kind of accuracy, you need to select 2
One for the start of the curve, and one for the end.
Lemme know if this helped at all
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS