Assistance with Sirens on Add-on vehicles

I feel stupid with this one, usually I can usually figure it all out on my own... I am using the added police vehicles mod, which I have successfully used in the past. The issue is that I have added a few vehicles, they spawn, they drive fine, they are properly flagged as police/emergency, they have siren settings, they have police audio files assigned to them, and yet I only get a stock horn sound when trying to use my sirens... no lights, no sirens... just that stupid horn mocking me saying Ha-ha! you did it wrong! Any help would be great, although like I said, I've already made sure they had police audio hashes, emergency flags, and siren and light settings in the vehicles and car variations.