I get an error after configuration

Hello Claudio,
After you send me the link for the plugin. I did installed it and network activated.
But here is what I get on products page.

Warning: Division by zero in /home/lojas083/public_html/wp-content/plugins/woocommerce-credit-card-interest-table/wc-credit-cart-interest-table.php on line 717

If I change the location to product tab I get the error
Warning: uasort() expects parameter 1 to be array, null given in /home/lojas083/public_html/wp-content/plugins/woocommerce/woocommerce-template.php on line 795

If I change the location to the end of the page I get
Warning: Division by zero in /home/lojas083/public_html/wp-content/plugins/woocommerce-credit-card-interest-table/wc-credit-cart-interest-table.php on line 717

I am running wp multisites.
I am using a custom theme, I changed to twenty eleven and it worked, then I switched to Argentum which is a woocommerce theme by woothemes and I get the error
Warning: uasort() expects parameter 1 to be array, null given in /home/lojas083/public_html/wp-content/plugins/woocommerce/woocommerce-template.php on line 795

Can you please help me with this?

Thanks
Davys