Error to upload : avrdude: ser_recv(): programmer is not responding

Development Tools IDE 1.x
1

Hello,

Everytime i try to upload a new program to my Arduino Mega 2560 i have this message :

avrdude: Version 5.4-arduino, compiled on Oct 9 2007 at 11:20:31

  • Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/*
  • System wide configuration file is "/Applications/Arduino/0020/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf"*
  • User configuration file is "/Users/AirClem/.avrduderc"*
  • User configuration file does not exist or is not a regular file, skipping*
  • Using Port : /dev/cu.usbmodem1411*
  • Using Programmer : stk500v2*
  • Overriding Baud Rate : 115200*
    avrdude: Send: . [1b] . [01] . [00] . [01] . [0e] . [01] . [14]
    avrdude: ser_recv(): programmer is not responding
    avrdude: stk500_2_ReceiveMessage(): timeout

I run on Mac OS 10.8 and i have no problem to upload programs on my arduino UNO.

Does anyone know what is the problem ?

Thanks