Can't cast lightning strike?

[bacchist]

Windows 4.2.5, currently playing a level 13 druid. I can't seem to cast Lightning Strike for some reason. After entering the command to cast and then selecting target, nothing happens. It's quite odd. No message, no SP loss, nothing. If I spam ctrl+v I occasionally get a spell failure message and accompanying SP loss.

[Sphara]

I think a floor square of your target has to be lit for Lightning Strike.
If you see a monster in a corridor through infravision or telepathy, but the corridor is dark, you cannot cast LS on the monster.