no sound

[jadejackellie]

hi lads fitted a mercury modulator so can watch
vu solo2 in bedrooms,works great on sd channels
but if i put a hd channel on i get no sound just picture
only way i get sound on hd is if i press audio button
and turn digital down mix to on ,but that way i dont
get my better sound thru my amp like dolby digital
bit of a pain having to turn it on/off all the time,is there a way
were i can get both working,thanks