XBee Configuration Fine BUT hurdles

I used my Duemilanove to access the XBee's and also programming their firmware ,everything works fine, I even checked the communication with default settings that is working prefect BUT as soon as I use a different PAN ID, EVERY-OTHER THING SIMILAR (offcourse same pan id for all the xbee's that is 115E for all) the communication just does not happen's , i recently finished the programming after upgrading their firmwares to 10CD from 10EC ,I'm using XBee pro's.

What could be the problem?

EDIT: OTHER THING IS THAT XBEE REPLIES ON THE TERMINAL FINLEY FOR EVERY '+++' THERE'S A OK BUT AFTER THAT NOTHING IF I TYPE LIKE 'ATID' ETC THAT IS NO REPLY FOR AT COMMANDS AND THIS WAS HAPPENING EVEN WHEN THE SETTINGS WERE DEFAULT BEFORE EDITING THE PAN ID AND XBEE'S WERE COMMUNICATING AT THAT TIME WITH EACH OTHER.

Anyone man! just on the verge to complete it!