Can't plug my Mp5 to my TV set
 

I have a "Portable 311 player" (PSP clone). It works without issues, but when today I bought a RCA plug (it goes in the left headphone plug with the standard 3 RCA plugs for the TV) to connect it to my TV set, I get nothing. Setting the player on NTSC makes my TV (actually, all the 3 TV sets of my house) not respond at all, like if nothing was connected to it. Setting the player to PAL mode gives a really faint signal which looks like if I was watching a scrambled channel, and then it vanishes, again not getting any picture at all. I tried with two different pairs of plus and nothing. Is there anything I can do?