Alright, blank page was about my BitPay plugin. If I choose payment with BitPay it should redirect to their site to finalize payment.

Code:
[23-Oct-2014 09:58:07 CST6CDT] createInvoice error array (
  'type' => 'limitExceeded',
  'message' => 'Invoice not created due to account limits, please check your approval levels',
)
[23-Oct-2014 09:58:07 CST6CDT] PHP Fatal error:  Call to undefined function zen_remove_order() in /home/vibraint/public_html/includes/modules/payment/bitpay.php on line 152
It looks like COWOA is not compatible with standard Zone Rates shipping module from ZC. Always shows "The shipping rate cannot be determined at this time".
Hmm, how to get into this?