Re: Connectivity problem...
I'm no expert, but don't most switchers require a fully wired SCART connection? At the very least, it'll require the switching signal on pin 8 to tell it which signals to forward on to the TV, I would have though. By using a phono-to-Scart converter, you're effectively only connecting three of the 21 scart pins.
Just a stab in the dark, but it might have something to do with it.
And welcome to the site, by the way!