Missing audio when playing backups

[Tha Shiznit]

The only game i`ve encountered this on is ISS Pro 2 (PAL). I`ve copied it using Clonecd on the slowest settings and with all relevant boxes ticked, but the in game main menu music is missing. This is no problem for me coz it`s annoying anyway, but the SFX and startup music are all there and the game plays fine so i`m afraid i`m as puzzled as you.