Problem with building simple theremin

This is my first post! Hello everybody
well. I´ve construct this theremin (http://www.thereminworld.com/pics/schematics/simple.jpg)
I think the sound is great(it´s a sine wave i think), but something is wrong...
1.To make the theremin sound, i have connected the "Ground(of my house electric connection" to the theremin "antenna out-cable)", and a 80cm lenght cable(as antenna) conected to all the theremin "ground-outs"...exactly the inverse of the schematic.
2.To make the sound change(oscilate) i have to TOUCH both ground and antenna wires. the more i touch the cables, the lower the frecuency signal is.
Somebody can help me?Somebody knows were is the problem?
Thank you.
I´m from Argenina, and i apologize for my english!!!
Enjoy the new year!

Hi,

The antenna in actuality acts as the plate of a capacitor that is part of the variable oscillator's tank circuit. It is kind of amazing that you are getting any sound at all -- in fact, your receptacle's ground may not really connect to a good earth ground.

The ground through a cable that isn't connected to anything can actually work... though not as good as an earth ground.

You may want to reverse your connections... that is, connect the pitch antenna to the pitch oscillator and the connect the ground to yourself via a wrist strap. (I personally don't recomment that you connect to the ground of an AC receptacle -- if there happens to be a wiring error you could get a dangerous shock.)

Keep us posted on your results.

Hello!
First of all: Thanks for the answer.

"You may want to reverse your connections... that is, connect the pitch antenna to the pitch oscillator and the connect the ground to yourself via a wrist strap. (I personally don't recomment that you connect to the ground of an AC receptacle -- if there happens to be a wiring error you could get a dangerous shock.)"
I reverse the connections, but there is no sound now. Connecting the ground to myself nothing changed.
In the place of the variable resistance(20k) i put a 22k non variable resistance.The other cmponents are the ones named on the schematic.
Now i´ve set the theremin as it was before. And still the problem...
Another reason for this problem?
Is the schematic all right?
Should i try with another schematic?
Thank you!