Apple TV set up help needed

[TUD1]

I got the Apple-TV for Christmas for the purpose of playing Youtube through my phone into the TV. I ordered an HDMI to three RCA-cable about a month ago, and it finally came. But now, with the Apple-TV plugged in, the extrernal RF-modulator won't even come on. Please help. I'd hate to know this thing cost so much and I can't even use it.

PS - a phlat skreen TV is absolutely NOT an option. If it can't be used with my CRT-television, I'll just get rid of it.