How to changes project owner using ZohoProject API'S

How to changes project owner using ZohoProject API'S

Hi Team, We are using Zoho Project API to create/Update projects, when we are triying to change project owner for the existing projects its throwing this error {"error":{"code":6401,"message":"Unauthorized Access"}}. Please let me know how do i change project owner for the existing project using API's

We are using Token of current project owner.

Sample Post URL -
https://projectsapi.zoho.com/restapi/portal/ComapnayName/projects/37792400000000/?authtoken=0023djskdfff&name=test66&strict_project=1&status=active&UDF_CHAR1=Fixed Price&UDF_LONG1=6543&UDF_CHAR2= test.test.test.test.kamal.s@mail.com&UDF_CHAR5=BU2&start_date=07-31-2017&end_date=09-28-2017