Unusable Signal for PS2

Question

I have a RCA Stereo Monitor Colortrak Plus with the red yellow white inputs in the back. I tried hooking my PS2 in and since there is no TV/Video button I checked all the basic channels like 2,3,4,5--didnt work, then I bought a universal remote and hit the TV/Video button but all that popped up was a black screen saying "unusable signal". What's the problem and what to do???