(這個問題剛才已經貿post 在別的討論區, 但我想應該屬於這一區, 再post一次, 不好意思)

請問在選擇結帳後, 進入出貨方式選擇的畫面時, 網頁最上方出現以下訊息. 是什麼原因? 該如何修正?

Warning: Division by zero in /home/healthid/public_html/includes/classes/shipping.php on line 79

Warning: Division by zero in /home/healthid/public_html/includes/classes/shipping.php on line 80

又, 若忽略上方的訊息, 選擇一個出貨方式後按"繼續", 則無法完成交易, 只出現含以下訊息的空白頁面. 請問是什麼原因? 該如何修正呢?

Warning: Division by zero in /home/healthid/public_html/includes/classes/shipping.php on line 79

Warning: Division by zero in /home/healthid/public_html/includes/classes/shipping.php on line 80

Warning: Cannot modify header information - headers already sent by (output started at /home/healthid/public_html/includes/classes/shipping.php:79) in /home/healthid/public_html/inc/twe_redirect.inc.php on line 27

先謝謝各位幫忙解答.