radio button value not showing in mysql table

This seems like a small problem but I can't seem to find the solution. I created a form on a web page. After the form is filled out, a confirmation email is sent to the person who filled out the form and a mysql table is populated with the information from the form. Everything works good except for one little thing: the value of the radio button is not showing up in the table.

Here's the form: http://www.webdevpractice.com/genoptix/CE/register.php

Here's the table on the webpage: http://www.webdevpractice.com/genoptix/CE/admin/index.php You will see that the Contact Me column is not filling up.

Here the php insert code on the registration form page:

if ((isset($_POST["MM_insert"])) && ($_POST["MM_insert"] == "registration")) {
  $insertSQL = sprintf("INSERT INTO registrants (registrant_id, first_name, last_name, medtech_id, job_title, company, city, `state`, email, phone, contact) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)",
                       GetSQLValueString($_POST['registrant_id'], "int"),
                       GetSQLValueString($_POST['first_name'], "text"),
                       GetSQLValueString($_POST['last_name'], "text"),
                       GetSQLValueString($_POST['medtech_id'], "text"),
                       GetSQLValueString($_POST['job_title'], "text"),
                       GetSQLValueString($_POST['company'], "text"),
                       GetSQLValueString($_POST['city'], "text"),
                       GetSQLValueString($_POST['state'], "text"),
                       GetSQLValueString($_POST['email'], "text"),
                       GetSQLValueString($_POST['phone'], "text"),
                       GetSQLValueString(isset($_POST['contact']) ? "true" : "", "defined","'Y'","'N'"));

I used phpMyAdmin to create the db and the table. I set the contact field as follows:

Type: ENUM

Lengths/Values: 'n','y'

Default: None

Collation: utf8_unicode_ci

Can you spot the problem?