Notice: Undefined property: in currency.php

Hello,

I am still configurating Hikashop (website it is not published yet).
I found an other error-message: It appears during the chickout-process and also in the backend.

Notice: Undefined property: stdClass::$tax_amount in /homez.428/monpetit/www/administrator/components/com_hikashop/classes/currency.php on line 1526.

if(!empty($element->variants)){
				foreach($element->variants as $k => $row){
					if(empty($row->discount) && !empty($row->prices)){
						$this->selectDiscount($element->variants[$k],$discounts,$zone_id);
						if(!empty($element->variants[$k]->discount)){
							foreach($row->prices as $k2=>$price){
LINE:1526: addDiscount($element->variants[$k]->prices[$k2],$element->variants[$k]->discount,$discount_before_tax,$zone_id,$element->product_tax_id);

SOLVED.

I had an error in tax-rate and tax-category.

A product refered to a tax-category which I had deleted. I think this was the cause. After creating the category again, it worked.

Thank you.