I wager because you are using similar but different (pardon the jargon) interfaces.
Interface type COMPONENT: This is a 5 cables connection, 3 for video, 2 for audio.
Typical plugs colors, Red, Green, Blue + Red, White.
Interface type COMPOSITE: This is a 3 cables connection, 1 for video, 2 for audio.
Typical plugs colors, Yellow, Red, White.
Component is the desired connection of the 2, is suitable for HD, Composite is not.
You should NOT hookup Component to Composite (even though the plugs look the same).