Unable to send alerts to MS Teams from Rancher

I have tried using MS teams for rancher v2.5.9. Installed rancher alerting drivers for webhooks.

Steps followed

* Removed https:// from connector URL.
* group_by, group_interval, etc configured.

**cluster-info:**
* Rancher v2.5.8
* v1.19.15-rancher1-1
* On-premise
* rancher-monitoring:16.6.0
* rancher-monitoring-crd:16.6.0
* rancher-alerting-drivers:1.0.200

**Issue**
* No error is found while saving config.
* Also no alerts were fired from Alertmanager to MS Teams.

Please help. Thanks in advance.
Reference:
[https://wyssmann.com/blog/2021/09/rancher-2.5.x-monitoring-and-alerting-with-ms-teams/](https://wyssmann.com/blog/2021/09/rancher-2.5.x-monitoring-and-alerting-with-ms-teams/)
[https://www.bookstack.cn/read/rancher-2.5.8-en/d191f7112840b857.md?wd=benchmark#webhook](https://www.bookstack.cn/read/rancher-2.5.8-en/d191f7112840b857.md?wd=benchmark#webhook)