Test with auth_test_plugin

[VID Vuong]

I am using MySQL 5.6.30, and try to use auth_test_plugin.
The plugin is installed correctly, and I create a user as below:

CREATE USER jtest1 IDENTIFIED WITH test_plugin_server AS '123';

then connect to the server through MySQL ODBC connector 5.6.30 with the connection string with "plugin_dir" option as below:
DRIVER={MySQL ODBC 5.3 ANSI Driver};server=localhost;port=<port>;uid=jtest1;pwd=123;plugin_dir=<the location of the plugin>

The plugin is in work. The client & server side function all return CR_OK. But the logging in is denied, the error message says:

ODBC SQLSTATE=HY000 Native error=1045, message=[MySQL][ODBC 5.3(a) Driver]Access denied for user 'jtest1'@'localhost' (using password: YES)

What's the problem in it.