That seems correct to me.
I guess the plugin doesn't run correctly.
Do you have other plugins? Do they run?
I realize that this a bit desperate, but just to be sure that the plugin/hook system isn't turned off.
Otherwise go to the plugin and edit it. Add this after the current line.
PHP Code:
$eventbituser[field19] = 'field19';
$eventbituser[field20] = 'field20';
You should get "field19 field20" below the username
/SK