Dear Sabari,
Authorization error comes when the User does not have authorizations to call the service. Please assign the needed authorization.
Please check the below things and hope it helps:
1. If the Application Webservice is working with Business User you should enter the same credentials in the Outgoing Communication Arrangnment for the Webservice to work.
2. If you have created an Incoming Communication Arrangment for the application Webservice and created a technical User for Access of the application webservice, then the same credentials has to be entered in the outgoing Communication Arrangment ( Which is built on the WSID out of PDI) for access of the application Webservice.
Regards
Anant