Just got the Olimex AVR jtag-usb. SF#PGM-00012. Installed the serial driver and moved it to com 2. looks ok on device manager. Tried several baud rates. Using AVR Studio 4.14 b589. Studio works with a STK500 and a borrowed AVR JTAGICE mkII. When using conn button… get conn failed. 
When I tried using the olimex jtag programmer, it would connect but programming the chip always failed. I just thought the chip I was using wasn’t compatible and ended up using the JTAGICE mkII instead. I haven’t had a chance to use the olimex jtag with anything else, though. What chip are you programming?
I have a stk500 board with ATmega128 and ATmega16 targets.
The Olimex doesn’t even get to that point. This morning I borrowed a Amtel JTAGICE and even without a target it communicates in Studio, but wants voltage on the target to proceded. The other question what is the lone red light on the Olimex for? I haven’t noticed any activity.