xbee problem

Hey I have a problem in my x-bee
When I tested my x-bee in x-ctu program it works very well at the first place but after awhile when I tested it by x-ctu the following message appeared
"unable to communicate with modem "

and when I enable API and tested it again the following message appeared on x-ctu
communication with modem … ok
Modem type =name unknown(ID=42949672481228488)
modem firmware version =

Any body have a solution to this problem please help me as soon as possibe

This message only appears when, PC com port baud rate and modem(XBee) baud rate are different. Try with the same baud rate with which you had programmed your XBee.