Error

I keep getting this error in the Checkout, and not sure how to fix it.

http://www.puregoodness.com.au/checkout/

Fatal error: Uncaught exception ‘Exception’ with message ‘Missing username and password.’ in /home/teatoxedadmin/public_html/puregoodness.com.au/wp-content/plugins/woocommerce-smart-send-australian-shipping/includes/smartSendUtils.php:117 Stack trace: #0 /home/teatoxedadmin/public_html/puregoodness.com.au/wp-content/plugins/woocommerce-smart-send-australian-shipping/includes/smartsend-checkout.php(153): smartSendUtils->__construct(NULL, NULL) #1 [internal function]: woocommerce_smart_send_checkout_js(”) #2 /home/teatoxedadmin/public_html/puregoodness.com.au/wp-includes/plugin.php(496): call_user_func_array(‘woocommerce_sma…’, Array) #3 /home/teatoxedadmin/public_html/puregoodness.com.au/wp-content/plugins/woocommerce/templates/checkout/form-checkout.php(47): do_action(‘woocommerce_che…’) #4 /home/teatoxedadmin/public_html/puregoodness.com.au/wp-content/plugins/woocommerce/includes/wc-core-functions.php(189): include(‘/home/teatoxeda…’) #5 /home/teatoxedadmin/public_html/puregoodness.com.au/wp-content/plugins/woocom in /home/teatoxedadmin/public_html/puregoodness.com.au/wp-content/plugins/woocommerce-smart-send-australian-shipping/includes/smartSendUtils.php on line 117