Hi Sahil,
Check the values of schema user details in sapuser table.
SQL> select * from "OPS$<SID>ADM".sapuser;
If you don't fount insert using below command:
SQL> INSERT INTO "OPS$<SID>ADM".SAPUSER VALUES ('SAPR3P','password');
if found the entries try to change the password for schema user and then try.
Brtools-->additional functions --> Change password of database user
Regards,
Lakshmi