Re: GTP USB programmer
Hi,
Afraid I cannot help you specifically with that programmer as I cannot see any real detail on the Indestructables site.
That message would imply either the PC software/ driver is not correctly installed or your 2550 chip is not correcly programmed or somewthing is wrong with the circuitry around the usb socket to the pic.
If you are not using the pcb then check the usb socket, its so easy to connect them the wrong way round.
The capacitor on pin14 VUSB is must be correct.
Without knocking that programmer, but if you cannot get it to work easily, then if it was me, and being as you have the 2550 chip and the ability to program it I would simply build a Pickit2 Lite / clone as featured many times here.
It works well and offers so much more than that programmer you are trying to make.