HI. Just I solved my problem and just access the forum to communicate it. If the TFT device is in black absolute and there is not even a gray image background, you should adjust the potentiometer in the adapter shield. I recommend you check this: just in the pin opposite to the pin marked as "JP2" on the TFT shield, if there is no a voltage slightly above 2.5 volts no light whatsoever, you will get a black screen. You must adjust the potentiometer even without running softare, until the TFT reach a light gray background. Turns clockwise increase the voltage. The reference is about 2.6 volts in the pin marked in the photograpy. Try it and see how it works. The potentiometer is like a brightness control but with a very critical threshold. I was tracing signals with oscilloscope this afternoon looking for the failure. I bought a second pair of TFT and ADAPTER shields in Womarts and for this reason I knows the problem was located in the adapter shield. Very simple? I must be an idiot for not having tried to adjust the potentiometer first before buying another pair of shields. :-)
More simple: if you get a blank (no gray) screen, turn clockwise the potentiometer, without running software, until you reach a light gray background. ;-)
Sorry, but I don'n know how upload the photo in this post. You can see it in
http://www.sepca-sctfe.org/downloads/arduino.jpg