Somehow after i put siren files into the vehicles folder and inport it it always turns out to be 15.81 MB instead of the max. 15.75 MB barrier.
This way all of my sirens are muted and i did everything correctly and followed the read me.
I put 4 files into the vehicles folder, then imported it with openformats (vehicles.oac) and shit happened.
Thx for any help :)