wpdb->insert problem

I’m having some trouble with wpdb->insert. From everything I’ve read, the insert below should be formatted correctly. The database has a table named Directory with four columns as named.

$insertresult = $wpdb->insert('Directory', array( 'dir_id' => '4', 'U_ID' => '2227', 'contactname' => 'contact', 'contactnamedisplay'=>'1'));

This is my first time working with $wpdb… I can easily do the same with a regular database query, but I’m trying to play by WP’s rules. Any idea where I’m messing up?

Thanks.