Unable to get redirected to the callback URL after user signature

Hi,

I use Adobe Sign REST APIs v6, I added the callback URL in the following format:

POST - https://api.na2.echosign.com/api/rest/v6/agreements

{

    "fileInfos": [{

        "transientDocumentId": "<the-transient-document-id>"

    }],

    "name": "Redirect 2",

    "participantSetsInfo": [{

        "memberInfos": [{

            "email": "<xxx@yyy.com>"

        }],

        "order": 1,

        "role": "SIGNER"

    }],

    "postSignOptions" : {

         "redirectDelay":1,

          "redirectUrl" : "https://www.google.co.in/"

     },

    "signatureType": "ESIGN",

    "state": "IN_PROCESS"

}

Did I miss anything which is causing me the issue which is why there is no redirection on completion of user signing?