Merge Button using GitHub API

I am trying to merge Pr using the merge button API 
https://developer.github.com/v3/pulls/#merge-a-pull-request-merge-button

I have tried to send the commit_message and commit_title params in body and in headers but with no success result, the Pr is merged successfully but the commit_message and commit_title aren’t affected. 

Hey @ahmedabdraboh

Thank you for being here! Could you please send us the full output of a curl -v request that demonstrates the problem?

http://curl.haxx.se/

That should help us investigate the issue. Also, please make sure you mask any sensitive information like OAuth tokens and Authorization headers in the output of the curl command. Please send the output to https://github.com/contact. And include a link to this thread to give support some background on the ticket.

I hope this helps!

Best,
Andrea