On the new backup target, do the following:
1. "su - amanda"
2. edit ".amandahosts" like so (replacing amserver.domain.com with the proper FQHN):
localhost amanda
localhost.localdomain amanda
amserver amanda
amserver.domain.com amserver
3. "exit"
4. Use "ntsysv" to enable the "amanda" service (client)
5. "service xinetd reload" to make the change effective immediately
6. Now try "amcheck" again, if you're not using anything fancy like encryption or firewalls it should work.