Hello friends..
If you are using PLSQL developer to connect to the ORACLE database may have faced the problem "SQL*Net not properly installed".
This problem occur beacause ORACLE_HOME and the oci.dll path location may not have been configured in the preferences.
To do this, go to Tools>Preferences.
Now set the Oracle Home as the location of the ORACLE_HOME variable or where the Oracle is installed. In my case it is:
C:\Oracle\DataBase\product\10.2.0\db_1
After this set the oci.dll file location just under the Oracle Home text field.In my case it is:
C:\Oracle\DataBase\product\10.2.0\db_1\bin\oci.dll
click Apply>OK
Now restart the PLSQL developer. This should solve the problem.
Cheers..