Unable to achive Destroy 5 Japanese Aircraft objective

[ralfmartin73]

I am replaying the US Pacific campaign and in the Guadacanal Scenario there is the objective

Destroy 5 Japanese Aircraft (This would give me a new Air commander)

I have destroyed 4 aircraft and from a certain point in the scenario, no additional enemy aircraft is showing up, I use #orbitalcommand on the last turn, there is no additional japanese aircraft on the map. How can this objective be achieved?