If you have tested connecting both to kiss directly and doens't works, (it's logical because you select one or another in menu), then what I would do is to do a phisical separation of signal. This is a simply signal of video and audio, so try to find a cable for that.
I mean if put output to component first duplicate it, so find 1 cable (1 component input and 2 component output), and fater that find 1 cable component to SCART.
I dont know if you can understand what I mean, you will lost a little bit of quality but depending of the quality of cables and distance will be not too much.
I think you needs cables like this (in http://es.kelkoo.com/b/a/ss_scart.html
) try to find near your live, or search in internet.
Hope this helps