When trying to connect to an instance in Performance Analysis for Oracle, it can't connect and the error message indicates that it is trying to connect to the wrong hostname for that server.
Faulty entry in tnsnames.ora file.
Check your TNSNAMES.ORA file on your client machine to make sure that the hostname for the instance you are trying to connect to is pointing to the correct hostname for that instance.
Also if you have multiple Oracle homes, make sure Performance Analysis is finding the correct tnsnames.ora file that you think it should be using. In general Performance Analysis will use the default Oracle home, but you may have to change your PATH environment variable so that the correct path is listed first.