default email type

booking.emails.inc

@@ -9,6 +9,7 @@ function booking_manual_email()
 	$group_text = "";
 	$prefix = t("<p>Send a manual email to people registered for this event.</p>");
 	$email_options_array = array();
+	$email_options_array['NULL'] = "---";
 	$email_options_array['registration'] = 'Registration Successful Email';
 	$email_options_array['balance'] = 'Balance Outstanding Email';	
 	$email_options_array['complete'] = 'Payment Complete Email';	
@@ -31,7 +32,7 @@ function booking_manual_email()
 		'#type' => 'select',
 		'#title' => t('Email Type'),
 		'#required' => TRUE,
-		'#default_value' => '',
+		'#default_value' => 'NULL',
 		'#options' => $email_options_array,
 	);