I used AVR Studio6.2 on my PC.
I updated AVR Studio 7.
Code build is OK, but cannot download firmware.
When I connect a JTAGICE3 with a PC, AVR Studio 7's device programming shows information of JTAGICE3.
So I think that I can be connected.
However, Read button of "Device signature" does not become Active even if I push "Apply" button of the software.
In this case please tell the points that you should check.