WP code to insert row of data into a table is not working


I am trying to insert a row into a table.

Given below are the various functions to create table. insert data into the table- but its not working. Also given below is the sample output showing all fields that are being attempted to be inserted.

/* Function: Insert Zillow property data into table
* Input: $zillowid String, $date DateTime
* Output: Boolean
function zillowInsertData($zillowid, $date_val, $postid, $url) {
global $wpdb;
$table_name = $wpdb->base_prefix."Zillow";
if(trim($date_val) == '')
$date_val= string2DateTime("0000-00-00");
$sql = "INSERT INTO $table_name (ZillowID, PostID, PropertyURL, DateUpdated) VALUES ($zillowid, $postid, $url,$date_val)";
return $wpdb->query($sql)===1;

echo " Values being inserted- Zp id=" . $current_zpid . ", postid=" . $post_id, "url=" . $propertyurl;
zillowInsertData($current_zpid, "", $post_id, $propertyurl );

About to insert row in Zillow table Values being inserted- Zp id=51605333, postid=111url=http://www.zillow.com/homedetails/1457-Golf-Course-Dr-Windsor-CA-95492/51605333_zpid/

What am I doing wrong here?