Using Plsql to connect Oracle error, sql*net not properly installed and TNS: Unable to resolve the specified connection identifier

1.64-bit Oracle client on 64-bit machine.
Then install the PL/SQL Developer, but connect the Oracle old newspaper with this error:

Workaround: Install the 32-bit Oracle client on a 64-bit machine. This will make the connection successful.

Basis:
From the installation point of view, the 32bit platform (operating system and hardware system) only support 32bitORACLE installation;
64bit platform supports installation of both 32bitORACLE and 64-bit Oracle

2. Reinstalling the 32 Oracle client solves the first problem, but then uses the Plsql connection to error: "TNS: Unable to resolve the specified connection identifier"

Workaround:

Using Plsql to connect Oracle error, sql*net not properly installed and TNS: Unable to resolve the specified connection identifier