After I setup amanda,
I tried to backup test with command "amdump hostname" from amanda user (amandabackup).

but it ended less than 1 seconds,
and in the log (/etc/amanda/hostname/logs),
there came out only "amdump.20180425*****" file.

in the file, contents is like below:
=============================================
amdump: start at Wed Apr 25 18:05:13 KST 2018
amdump: datestamp 20180425
amdump: starttime 20180425180513
amdump: starttime-locale-independent 2018-04-25 18:05:13 KST
planner: running as user "amandabackup" instead of "root"
driver: pid 10556 executable /usr/libexec/amanda/driver version 3.3.5
driver: Did not get DATE line from planner
amdump: end at Wed Apr 25 18:05:13 KST 2018
amdump: unlink /etc/amanda/hostname/logs/amdump.20180425********

Is anyone how to solve this?