don't work my p - mp 868 radio sistem

I put the Modem VID (IV) for al radio modem the same,
for master DH-0000, DL-FFFF and for 1 Rf modem DL,DH master, and 2 Rf modem DL, DH master.
10 days work fine, but now master not send data at Rx pin. I check modem parameter for master,but work fine.
What could be the problem?
Please help, misu