You're using single quote strings which don't interpolate. So the request you end up actually sending is:

http://www.chollonet.com/trucoteca/truco.php?idjuego=$id&plataforma=4

and not

http://www.chollonet.com/trucoteca/truco.php?idjuego=<whatever-$id-held>&plataforma=4

HTH.

bbfu
Seasons don't fear The Reaper.
Nor do the wind, the sun, and the rain.
We can be like they are.