aws profile on PMM

My DB instances (dev/stg/prod) are running on rds, so I have configured PMM one of the EC2 instance which hosted on stg environment.
when I tried to add RDS instance on PMM, I am able discover only staging rds instances , but not able to see other dev/prod instances and I’m getting below error.

AccessDenied: User: arn:aws:sts::ARN-ID:assumed-role/****** is not authorized to perform: rds:DescribeDBInstances status code: 403, request id: ****

please let me know is there any way to add a aws profile into multiple account or any other way to fix the issue.

Thanks in advance.