The usage of webhook for the team's private Git repositories

I am trying to test the webhook usage for lp:~oem-solutions-engineers/oem-dev-tools/+git/oem-scripts but it won't call the webhook I added. Is there any problem?
I have enabled git push,merge proposal, active and use secret.
Recent deliveries of https://code.launchpad.net/~oem-solutions-engineers/oem-dev-tools/+git/oem-scripts/+webhook/13229 is always empty.
Although I made https://code.launchpad.net/~fourdollars/oem-dev-tools/+git/oem-scripts/+merge/384887 for it.
It works fine if I added the webhook on lp:~fourdollars/oem-dev-tools/+git/oem-scripts.
How can I use the webhook on lp:~oem-solutions-engineers/oem-dev-tools/+git/oem-scripts?
It is weird that I can add the webhook on the team's Git private repositories but it won't delivery the events.