Arduino Mega2560 can't be programmed via USB

Using Arduino IDE 1.x
9

The same issue with my Mega2560. Reproduced with IDE 1.0.1 and 1.0.4.
I'm disappointed. It seems Arduino is NOT so user-friendly as people say.
Too much headache for too much money... It is more convenient now to buy Raspberry Pi with ADC chip if needed.

Here is my boot log:

/home/user/bin/arduino-1.0.4/hardware/tools/avrdude -C/home/user/bin/arduino-1.0.4/hardware/tools/avrdude.conf -v -v -v -v -patmega2560 -cwiring -P/dev/ttyACM12 -b57600 -D -Uflash:w:/tmp/build7626980947593966222.tmp/TempMonDS18B20.cpp.hex:i 

avrdude: Version 5.11, compiled on Sep  7 2011 at 19:34:16
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2009 Joerg Wunsch

         System wide configuration file is "/home/user/bin/arduino-1.0.4/hardware/tools/avrdude.conf"
         User configuration file is "/home/user/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/ttyACM12
         Using Programmer              : wiring
         Overriding Baud Rate          : 57600
avrdude: wiring_open(): releasing DTR/RTS
avrdude: wiring_open(): asserting DTR/RTS
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer

avrdude done.  Thank you.