Unable to properly connect sony dvd to tv to play movie

I have an older tv and I use a digital converter box daily. Now I want to watch a dvd, but when I disconnect the digital converter and connect the 3 cables (yellow, red and blue(?))from the dvd player to the tv, no blue screen appears. When I turn on the dvd player the light turns green, display says stand by, then the light turns red. Does the light mean that the machines aren't connected correctly? I don't have enough cables to connect all 3 pieces of equipment.