I experienced that for zone messaging, zones numbers are important, not only the order but the number.
I have a project with 6 zones but as I did a lot of tests, one of the zones have the number 21 while the othes are 3,4,5,8,9
When a zone message is sent to all zones, the number 21 works but later..
As I can´t change those numbers I had to create new zones from the 21 and copy the content of the old ones.
I think it has to be due BA creates its files with the erased zones, although they are not used at the project.
Maybe is easy to fix...