# Begin of terminal interaction
$ strace ".guix-profile/sbin/samba/smbd"
stat64("/gnu/store/...-samba-4.5.0/etc/samba/smb.conf", 0xbfeb41b0) = -1
ENOENT (No such file or directory)
open("/gnu/store/...-samba-4.5.0/etc/samba/smb.conf", O_RDONLY|
O_LARGEFILE) = -1 ENOENT (No such file or directory)
stat64("/etc/localtime", {st_mode=S_IFREG|0644, st_size=2001, ...}) = 0
exit_group(1)                           = ?
+++ exited with 1 +++
# End of terminal interaction

Sorry for my brevity, I'll return to this issue at a later time.