mark24 on "newly created mysql table not found"

I'm new to WordPress and am trying to set up a table of customers with passwords. I created a new MySQL table named wp_qcustomer and inserted 2 rows with phpadmin. I think I have the syntax right as it works in tests with Wordpress tables wp_comments and wp_options, but the call to wp_qcustomer returns nothing. (See coding below)
Is there something else I have to do? Is there a wait period for the table to be updated? Is there a way to get any error messages being generated?

[insert_php]
global $wpdb;
$mylink = $wpdb->get_row("SELECT * FROM $wpdb->comments WHERE comment_ID = 4", ARRAY_A);
echo $mylink['comment_author'];

$mylink = $wpdb->get_row("SELECT * FROM $wpdb->qcustomer WHERE custid = 1", ARRAY_A);
echo $mylink['fname'];

$mylink = $wpdb->get_row("SELECT * FROM $wpdb->options WHERE option_id = 1", ARRAY_A);
echo $mylink['option_name'];

[/insert_php]