Gluster add arbiter fail

[root@test-glus2 ~]# gluster volume add-brick backups replica 3 arbiter 1 test-arbiter1:/exp/brick1/backups ​test-arbiter1:/exp/brick2/backups test-arbiter1:/exp/brick3/backups test-arbiter1:/exp/brick4/backups
internet address '​test-arbiter1' does not conform to standards
volume add-brick: failed: Pre-validation failed on localhost. Please check log file for details

[2017-09-05 20:55:17.194180] I [MSGID: 106482] [glusterd-brick-ops.c:447:__glusterd_handle_add_brick] 0-management: Received add brick req
[2017-09-05 20:55:17.194230] I [MSGID: 106578] [glusterd-brick-ops.c:499:__glusterd_handle_add_brick] 0-management: replica-count is 3
[2017-09-05 20:55:17.194243] I [MSGID: 106578] [glusterd-brick-ops.c:506:__glusterd_handle_add_brick] 0-management: arbiter-count is 1
[2017-09-05 20:55:17.194257] I [MSGID: 106481] [glusterd-brick-ops.c:312:gd_addbr_validate_replica_count] 0-management: Changing the replica count of volume backups from 2 to 3
[2017-09-05 20:55:17.257225] E [MSGID: 106408] [glusterd-peer-utils.c:119:glusterd_peerinfo_find_by_hostname] 0-management: error in getaddrinfo: Name or service not known
 [Unknown error -2]
[2017-09-05 20:55:17.317346] E [MSGID: 101075] [common-utils.c:3355:gf_is_local_addr] 0-management: error in getaddrinfo: Name or service not known

[2017-09-05 20:55:17.317412] E [MSGID: 106429] [glusterd-utils.c:1159:glusterd_brickinfo_new_from_brick] 0-management: Failed to convert hostname ​test-arbiter1 to uuid
[2017-09-05 20:55:17.317427] E [MSGID: 106256] [glusterd-brick-ops.c:1857:glusterd_op_stage_add_brick] 0-management: Add-brick: Unable to get brickinfo
[2017-09-05 20:55:17.317440] W [MSGID: 106122] [glusterd-mgmt.c:177:gd_mgmt_v3_pre_validate_fn] 0-management: ADD-brick prevalidation failed.
[2017-09-05 20:55:17.317475] E [MSGID: 106122] [glusterd-mgmt.c:980:glusterd_mgmt_v3_pre_validate] 0-management: Pre Validation failed for operation Add brick on local node
[2017-09-05 20:55:17.317489] E [MSGID: 106122] [glusterd-mgmt.c:2136:glusterd_mgmt_v3_initiate_all_phases] 0-management: Pre Validation Failed