VCR/s-video monitor question

I have an old VCR my brother gave me.

I'm trying to connect it to my Panasonic BT-S901Y video monitor (it has s-video)

I am using RCA composite out on the VCR, to an s-video adapter, into the monitor.

it doesn't work.

there is a signal after some experimentation, but it's just jagged snow.

some help?

thanks

ultimately i'd like to use this setup with an Atari 400.