AIR is being supported in between certain NBU versions not the NBU appliance HW itself....
BTW the error you are reciving stands for:
bperror -S 1591
No import SLP(s) found with compatible replication target device.
In the target domain, the import SLP is present, but the replication target device is not compatible.
So you need to modify appropriate Import SLP on target NBU domain to match the source device... IE MSDP -> MSDP
What are NBU/Appliance versions on source and target domains?
As stated above - AIR is supported between MSDP pools whether on Appliance (no matter model) or MSDP on BYO media server.
Please tell us more about the AIR / SLP config.