GitHub integration with RTC work item-Webhook issue

Hello team,
We are using our own on premise GitHub server inside our organization. Our ALM(RTC) server also on premise one.When we try to link RTC work item with Github commits by using webhooks getting below error.

webhooks error message:
Error message: We couldn’t deliver this payload: server misbehaving .

Any reason on this. Could you help on this.

If i try from RTC side by registering repositories also facing other issue.