No Error Message When Registration Fails

When a user fills out the registration form, and the plugin has an issue with something wrong, the user is taken back to the top of the form, (there is a tiny red vertical line) but there is no error message indicating what needs to be changed.

It also appears that if a user is deleted from user database base, and then that user attempts to register again under the same name or email address, the plugin does not allow that. This does not make sense.

So… how can I get a specific error message to show up when the registration form is not filled out properly? (or at least have the erroneous field highlighted?)

Thanks,
Edgar

https://www.ads-software.com/plugins/register-plus-redux/