Before you go chasing after hard to find products (though i don't know whether Schreck cable releases are that), just go to a shop and try some. I have used quite a few 'generic' cable releases - cheap and not so cheap alike - and have yet to find one that doesn't work. So just try some!
(I'm not suggesting, by the way, that something is amiss with your reported experience with cable releases, or something like that. Just that the odds are pretty good in favour of you finding a good one in any camera store, without having to 'go to lengths' to get one that's fine.)