Unable to communicate with modem

Queried modem from X-CTU after connecting Arduino Diecimila board with XBee shield but unable to talk to modem. Also unable to read modem config. Modem selected XB24; function set XBee 802.15.4; Version 10CD

What version of X-CTU are you using? The latest seems to be 5.1.4.1. There have been issues in the past where to talk to a specific firmware version, a sufficiently up-to-date X-CTU was needed.

The latest 5.1.4.1 Problem may have something to do with the Diecimila board. If I take out the micro-controller with the board at USB setting, X-CTU is able to query the modem successfully.