Fio Xbee communication

Both Fios have been uploaded with the same code.
Xbee series 1.
DH Xbee1 = SH Xbee2
DL Xbee1 = SL Xbee2
DH Xbee2 = SH Xbee1
DL Xbee2 = SL Xbee1
Few months ago you advised me on some serial communication problem to introduce somewhere

while(Serial.available == 0){
}

do you think that may alleviate my problem?