Flame Weapon vs Buildings IE

It's been reported that an Internal Error occurs when a Flame Tower brings a building down to half damage.
I checked with the Flamethrower and it also does it.

They use similar weapons with the same warhead and projectile, everything is referenced properly.
Anyone see any problems here?

;Flame Tower
; rapid fire machine gun
[Vulcan]
Damage=125
ROF=50
Range=4
Projectile=FlamBall
Speed=12
Warhead=RAF
Report=FIREBL3
Anim=MGUN-N,MGUN-NE,MGUN-E,MGUN-SE,MGUN-S,MGUN-SW,MGUN-W,MGUN-NW
;UseFireParticles=yes
;AttachedParticleSystem=FireStreamSys

; Flame Balls
[FlamBall]
Image=FlamBall
SubjectToCliffs=yes
SubjectToElevation=yes
SubjectToWalls=yes
AA=no
AG=yes

; Red Alert 'Fire'
[RAF]
Verses=90%,90%,90%,60%,25%,25%,100%,100%,100%,100%,100%
InfDeath=4
AnimList=RAFLAM
Sparky=yes
Fire=yes
;Bullets=yes
ProneDamage=50%;70%
CellSpread=0.6

Remove Sparky=yes from warhead and it should be fine

Brilliant, thanks.