Ball Lighting + Wall of flame interaction

Hi, I'm playing around with+ Flame wall and Ball Lightning and have noticed that the added Fire damage that is added if it should pass the wall dissipates before the projectile has finished it's cast duration. Not sure if it's just the visual or also the effect. I'm running Flame wall = Fortress + Persistence + Mobility and Ball Lightning = Overcharge + Stormfire + Deceleration.