Error when setting option: Do not Display Product, if child products also out of

[jeoff]

I am using VM 2.0.8e on Joomla 2.5.6. No other VM plugins are installed.

When I go to: Configuration - Shopfront and set the option "Do not Display Product, if child products also out of stock"
I get the following error on the front page of the shop:

EDIT: Some more info! I only see this error when logged in as a Joomla Superuser. Normal users or visitors who did not sign in do not see this error message

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vmError: exeSortSearchListQuery Column 'product_sales' in order clause is ambiguous SQL=SELECT * FROM `idrqt_virtuemart_products_nl_nl` as l JOIN `idrqt_virtuemart_products` AS p using (`virtuemart_product_id`) LEFT JOIN `idrqt_virtuemart_product_prices` as pp ON p.`virtuemart_product_id` = pp.`virtuemart_product_id` LEFT JOIN `idrqt_virtuemart_product_shoppergroups` ON p.`virtuemart_product_id` = `idrqt_virtuemart_product_shoppergroups`.`virtuemart_product_id` LEFT OUTER JOIN `idrqt_virtuemart_shoppergroups` as s ON s.`virtuemart_shoppergroup_id` = `idrqt_virtuemart_product_shoppergroups`.`virtuemart_shoppergroup_id` LEFT OUTER JOIN `idrqt_virtuemart_products` children ON p.`virtuemart_product_id` = children.`product_parent_id` WHERE ( p.`published`="1" AND (p.`product_in_stock` - p.`product_ordered` >"0" OR children.`product_in_stock` - children.`product_ordered` > "0") AND ( s.`virtuemart_shoppergroup_id`= "2" OR s.`virtuemart_shoppergroup_id` IS NULL ) ) group by p.`virtuemart_product_id` ORDER BY product_sales DESC LIMIT 0, 5
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Any ideas?

The reason why I want to set this option in the first place (in case I understand this wrong).
I am setting up a website that sells clothes. I create a parent article for a clothing item with 0 in stock. I then create child items through the Custom Fields tab for each size I have of that item (so the same item, but then size Large, Medium, Small etc.) wich each child item having a certain number of stock.

This way I would have to set the option for the parent item to show: Do not Display Product, if child products also out of stock

But like I said I see the error message above on the front page. The store seems to work OK for the rest.

Any help would be greatly appreciated!