arduino configure xbee module

Hi, i'm trying to configure an xbee series 2 module under mac. I have an arduino uno and I'd like to use it to configure the module, so I set the jumper on xbee shield on USB position (both of them), I removed the atmega from arduino, download coolterm, connected arduino with xbee shield and xbee module to usb port. I lunched coolterm (anebled local echo option) and I can connect via serial port to the board but when i digit (I waited 2sec before digit) +++ i dont get any OK message (I did not typed "return" botton). Any hint?