Artillery functions in a parabolic arc. It is not meant to hit its target at the peak of its arc, but rather on the downward slope. Therefore, they'd be trying to drop shells onto the dragon, not "shooting" at him in the traditional sense, but lining up the end of the parabolic arc so that it would fall on him. The problem with this is that you never told them your location was near the dragon. Generally when calling in an artillery or airstrike of any kind that is within 300 meter proximity to your position you alert the artillery and/or aircraft with a "Danger close" warning.
This is what it would look like:
"Steelrain, steelrain, this is Hitman calling in fire mission, popeye uniform 059 098 038 degrees 200 meters, danger close"
"Roger that hitman, splash in 5 seconds."
This alerts the artillery crew that you are nearby and they should probably try to not hit you. You didn't do any of that. You just said "Shoot at the dragon."
Anyway, it's over and done now. Just keep that in mind for future reference.
@[member="Vulpesen"]