programming mega by uno as isp

i am trying to program in arduino mega adk as instructed here http://arduino.cc/en/Tutorial/ArduinoISP.. but
Binary sketch size: 1,632 bytes (of a 258,048 byte maximum)
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer
this error is comming .. actually my mega is some how damaged but it is still able to upload if using an external programmer. I used avr programmer to program it ,it works but not with uno..