Setup Slack Webhook - Error

Tried to setup a webhook to my slack channel. Followed instructions found in Notification. I get this error. How do i make notifications work in slack?

{‘retry’: 0, ‘log’: <function log at 0x7f583462cc80>, ‘site’: u’site1.local’, ‘event’: None, ‘method_name’: ‘frappe.integrations.doctype.webhook.webhook.enqueue_webhook’, ‘method’: <function enqueue_webhook at 0x7f583462b758>, ‘user’: u’gacaljenette@gmail.com’, ‘kwargs’: {‘doc’: <erpnext.stock.doctype.delivery_note.delivery_note.DeliveryNote object at 0x7f583487eed0>, ‘webhook’: {u’webhook_doctype’: u’Delivery Note’, u’webhook_docevent’: u’on_submit’, u’name’: u’Delivery Note-on_submit’}}, ‘async’: True, ‘job_name’: u’frappe.integrations.doctype.webhook.webhook.enqueue_webhook’}
Traceback (most recent call last):
File “/home/administrator/frappe-bench/apps/frappe/frappe/utils/background_jobs.py”, line 97, in execute_job
method(**kwargs)
File “/home/administrator/frappe-bench/apps/frappe/frappe/integrations/doctype/webhook/webhook.py”, line 73, in enqueue_webhook
raise e
HTTPError: 400 Client Error: Bad Request for url: https://hooks.slack.com/services/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