Z offset and lightning effects

how can i make lightning effects go from a point in the air to a point on the ground. Ive tried using invisible flying units, but the start and end of the lightning is at positions of the units reguardless of their height.

Custom Script:

call AddLightningEx(codeName, true, GetLocationX(udg_tempPoint1), GetLocationY(wudg_tempPoint1), GetLocationZ(udg_tempPoint1) + heightofpoint1, GetLocationX(udg_tempPoint2), GetLocationY(udg_tempPoint2), GetLocationZ(udg_tempPoint2) + heightofpoint2)