Unable to enter programming mode. using AVRISP mkII for ATmega32U4

Hi all,

I try to program my custom board based on arduino leonardo using ATmega32U4. I can read the target voltage using AVRISP mkII on ATMEL STUDIO 6. It appears 4.6V, however when I try to read Device Signature:

Unable to enter programming mode.

Please verify device selection, interface settings, target power and connections to the target device. Look in the details section for more information.

I try to lower the ISP Clock but it is not working too. I also put pull up resistor 10K between rst and VCC and it also didn’t work. The AVRISP mkII LED act normally, all green after connected to the board. I suppose there is clock or rst problem. How I make connection test for rst and clock? Or anybody has the same problem?