failed to delete error about slack-cleaner HOT 4 CLOSED

$ ... --message --channel zc-alarm --user 'kenney.he' --before 20180122 --rate 1'
Running slack-cleaner v0.4.0
Deleting messages from channel zc-alarm
Will delete message -> kenney.he :  <@U8EM71DM5> set the channel purpose: get status alarms
Will delete message -> kenney.he :  <@U8EM71DM5> has joined the channel
Will delete message -> kenney.he :  <@U8EM71DM5> has left the channel
Will delete message -> kenney.he :  <@U8EM71DM5> has joined the channel

$ ... --perform
Running slack-cleaner v0.4.0
Deleting messages from channel zc-alarm
Failed to delete (cant_delete_message)->
{   u'purpose': u'get status alarms',
Failed to delete (cant_delete_message)->
Failed to delete (cant_delete_message)->
Failed to delete (cant_delete_message)->

0 message(s) cleaned.

    u'subtype': u'channel_purpose',
    u'text': u'<@U8EM71DM5> set the channel purpose: get status alarms',
    u'ts': u'1516560401.000017',
    u'type': u'message',
    u'user': u'U8EM71DM5'}
{   u'subtype': u'channel_join',
    u'text': u'<@U8EM71DM5> has joined the channel',
    u'ts': u'1516554103.000022',
    u'type': u'message',
    u'user': u'U8EM71DM5'}
{   u'subtype': u'channel_leave',
    u'text': u'<@U8EM71DM5> has left the channel',
    u'ts': u'1513721307.000207',
    u'type': u'message',
    u'user': u'U8EM71DM5'}
{   u'subtype': u'channel_join',
    u'text': u'<@U8EM71DM5> has joined the channel',
    u'ts': u'1513709543.000039',
    u'type': u'message',
    u'user': u'U8EM71DM5'}

$ docker run sgratzl/slack-cleaner -c 'slack-cleaner --token <token> --message --channel public --user '*' --before 20180122 --rate 1'
Running slack-cleaner v0.4.0
Deleting messages from channel public
Will delete message -> captainamerica :  Test
Will delete message -> captainamerica :  <@U04SW899U> set the channel purpose: Test public
Will delete message -> captainamerica :  <@U04SW899U> has joined the channel

3 message(s) will be cleaned.

Now you can re-run this program with `--perform` to actually perform the task.

$ docker run sgratzl/slack-cleaner -c 'slack-cleaner --token <token> --message --channel zc-alarms --user '*' --before 20180122 --rate 1 --perform'
Running slack-cleaner v0.4.0
Channel, direct message or private group not found
$ docker run sgratzl/slack-cleaner -c 'slack-cleaner --token <token> --message --channel zc\-alarms --user '*' --before 20180122 --rate 1 --perform'
Running slack-cleaner v0.4.0