1756-dnb connection error

i'm trying to interface a 1756-dnb to a couple devices. i've got the rsnetworx configuration complete and dowwnloaded to the device. when i go online in studio 5000, the scanner is faulted out. the code is "16#0108 connection request error: connection type (multicast/unicast) not supported".
what could be going on here? i'm using an l72s cpu and a 1756-dnb/a on the local chassis