That's executing the JS before profile update occurs. What you need to do is add jQuery and bind it to the click event for that checkbox field during the profile edit display. Example action as follows to do this.
Type: Code
Triggers: onAfterUserProfileEditDisplay
Access: Everybody
Method: jQuery
Code:
Code:
$( '#cb_disputebalance' ).click( function() {
if ( $( this ).is( ':checked' ) ) {
alter( 'This is an alert.' );
}
});