Calling gitlab api does not work when Accept MR methods

Hello:

Use this method

PUT /projects/:id/merge_requests/:merge_request_iid/merge

PRIVATE-TOKEN is validated correctly. It is normal to operate the merge request on the gitlab web interface. And in the call api execution has been reported 401，please help.

Req:

Http://git.xxxxx.com/api/v4/projects/14509/merge_requests/13/merge

Response:

{    "message": "401 Unauthorized" }

The current gitlab version is: GitLab Community Edition 8.17.8