bitbucket webhook with jenkins

Facing issues linking up jenkins with bitbucket.

We have setup a jenkins user with necessary build privilege. Curl command triggers the build correctly with the below URL.

http://autobuild:apiToken@myjenkins.com:8080/job/BQJobs-1.41/build?token=BUILDTOKEN

It fails when I add this URL to the bitbucket and trigger it via the webhook plugin. How should I configure the webhook so that it triggers whenever there is a merge in the master plugin ?

P.S. : There is no network issue. Error is scrambled html+js couldn't get much info out of it.