No sound from VCR to TV card with coaxial

[Ancient]

I get sound and picture from a TV aerial and Sky box when connected through a coaxial cable to a TV capture card.
However from a recent VCR I get picture but no sound.
Many years ago I had an Aims Lab TV card which played picture and sound through a coaxial for two old VCRs and a Sky box.
What has changed?
I do not wish to know how to connect the VCR by other means but just why it is now not possible to get sound.

 

[Ancient]

Should have noticed how few questions are answered before posting. Will try elsewhere.