fail to get signal

hej
I have bought 4 DIGIWR44 modem.after provisioning, only one of my modem getting signal to connect internet but rest of 3 are not getting signal.’
can you tell me should should be the problem?

If you have not already done so, please open a support request here:
http://www.digi.com/support/eservice/login.jsp?p=true
or, contact uksupport@digi.com