Prgramming atmega16u2 error

I have tried to program firmware to atmega16u2 on UNO broad. Seem it have done the program. But when I put on the USB cable to the computer. There's no more COM port for the UNO board. Even I tried to use the avrdude tools to reprogram the firmware It's always give this respond below

% avrdude -q -c usbtiny -P usb -p atmega16u2 -U flash:w:Arduino-usbserial-atmega16u2-Uno-Rev3.hex:i -Ulfuse:w:0xFF:m -Uhfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0xFF:m -F

avrdude.EXE: error: programm enable :target doesn't answer. 1 avrdude.EXE: initialization failed,rc=-1 avrdude.EXE: AVR device initialized and ready to accept instructions avrdude.EXE: Device signature = 0x000000 avrdude.EXE: Yikes! Invalid device signature avrdude.EXE: Expected signature for ATMEGA16U2 is 1E 94 89 avrdude.EXE: NOTE: FLASH memory has been specified, an erase cycle will be performed To disable this feature, specify the -D option. avrdude.EXE: done. Thank you.

child process exited abnormally

I have just resolder the 16u2 and put a new chip on have the same problem Is there someone know what's going on and how to solve the problem