Nightfighting Rules

A few days ago we got an argument about Night Fight rules. It is like this;

A unit mixed with different weapons (i.e. a unit of kabalite with 9 splinter rifles and a dark lance) want to shoot an enemy unit. Dark Eldar player rolls 4 and 5 for Night Fight spotting distance which means 27 inches.

After mesured the range it is found that enemy unit is 25 inches away from one Kabalite model with splinter rifle which is closest one. Other models including kabalite model with Dark Lance is standing more than 27 inches away but kabalite with Dark Lance model is in 36" range of Dark Lance weapon.

One side claims that kabalite with Dark Lance can't shoot because it is not in Night Fight spotting distance. Other side claims that Night Fight spotting distance rolled for 'unit' not model so if unit sees enemy each model in the unit may fire as long as their weapons' range reaches enemy.

in BRB pg 95 under Night Fighting rule it says;

"
Roll 206 and multiply the result by 3, then measure the distance
between the two units (remember that distances
to/from vehicles are measured to/from their hull, and
not their guns). If the distance between the firing unit
and their target is higher than the total rolled, the unit
cannot fire at all in this Shooting phase, as they search
the dark for a target that never appears.
"

Well from my point of view it is clear that rule mentions the term 'unit' instead of 'model' (it also gives a clearance for vehicles). So it means that; if any model from the unit spots the enemy unit which they are searching for throught the darkness, whole models of the same unit also spotted that enemy unit too.

Do you experience similar arguments and how do you solve it?

You've hit the nail right on the head for me, p95 states that it's the distance between the units that is crucial, not the distance between individual models in the unit, therefore if any members of the unit are in range, the whole unit can fire.

You are correct. Its on a unit to unit basis, not model to model basis. Its easy to assume that as soon as one of the units models spots the target he directs the fire in that direction.