update_field with repeater returning true, not inserting

Hi there,

First: love your work. These plugins a re brilliant. Second: i have scoured this forum for solutions, but no dice. I have tried - honest!

The problem: I have an advanced custom field attached to a custom post type of 'events'. The parent is called "Event Listings" (event-listings) The repeater i wish to update is called 'Event Dates' (event_dates) The sub fields within the repeater are : event_date, event_time, ticket_url

this is the code I am running (hard coded for test purposes) to try and even insert some data to the listing:

$fid = 'field_518a7bc5774a8';
$data = array( 
    array( "event_date" => "20130510", 
              "event_time" => "all day", 
             "ticket_url" => 'TEST1' ), 
    array( "event_date" => "20130212", 
              "event_time" => "all day", 
             "ticket_url" => 'TEST2' ), 
$event_id = '358';    
echo update_field( $fid, $data, $event_id );

This returns true, but does not enter into the DB. Help!?