AIR for iOS error - Undefined symbols for architecture arm64:...

When I try to publish my game for iOS (.ipa), I'm getting an error (see image). There are no errors when I publish the .swf or when I publish it for Android (.apk), but when I change the target to AIR 23.0 for iOS, I'm getting this error:

I can't seem to figure what I have to do to fix this. Any ideas?

Thanks!