I just bought a plasma Philips 50PF7321D37. the HDMI port works great. But once I try to use composite port(by RCA cables), here the problems comes:

1) image has no color
2) image is not stable
3) no sound

I connect plasma with samsung dvd-player(which works perfect with old TV by RCA). I would wonder whether I miss something during setup or it's just a defective tv. :(