Bug? Registration/"Aircraft ID" Numbers not showing on some aircraft.

[A_Nonamus]

Anyone know why my registration numbers are not showing up on most aircraft? I only just noticed the problem after beginning to install the AI Helicopters packs.

The following aircraft are the only ones that DO show the registrations:
Cessna 182R RG
Learjet 45
Schweizer SGS 2-32 glider
Sopwith Camel
Concorde (FS2000 version) - very tiny but it's there

I have a few other addon aircraft installed but most of them have their registrations painted onto the textures, so those don't count.