how can i get sound?

have a sky box in france which was purchased in the uk.I purchased a Hypson tv in france which works via scart lead for sound and picture but when i connect via the co ax i do not get any sound only a picture have tried tunning the tv but will not get any sound. do i need to buy a tv in the uk for the sound to work or is it that this tv is a cheap model and i need to buy a well known make lg panasonic etc?
mike garcia