CMDB API - Access Denied for Admin account

CMDB API - Access Denied for Admin account

Hi,

I am using CMDB API to get assets related to particular CI (Business Service).
For that purpose, I am using below API with technician key from Admin account but I am getting error of 'Access Denied'.

API:
https://help-test/api/cmdb/cirelationships/<CI NAME>?OPERATION_NAME=read&TECHNICIAN_KEY=<ADMIN TECH KEY>

Here <CI Name> is Business Service name.

Response:
"message": "User does not have requisite permission to view relationships for CI other sites.",
"status": "Access is denied.",
"statuscode": 3015

Any suggestion? Do we need to assign any roles to this account. 
Note: There is no 'other site'.

                  New to ADSelfService Plus?