Different product url in parent and in subcategory

[hop]

Hello,
I have problem with my product urls. My product item is in parent category and in subcategory also.
In list of products for parent category has this product different url, than in subcategory.
The problem is, that the product url from parent category does not work and from subcategory it works.

Live site parent category list:
http://www.plenkybobanek.cz/latkovani-obchod/no%C4%8Dn%C3%AD-aio-plenky
Product url from parent category list:
http://www.plenkybobanek.cz/latkovani-obchod/no%C4%8Dn%C3%AD-aio-plenky/farma-detail     -not working

Live site subcategory list:
http://www.plenkybobanek.cz/latkovani-obchod/no%C4%8Dn%C3%AD-aio-plenky/extra-save-aio-plienky-pul-patentky
Product url from parent subcategory list:
http://www.plenkybobanek.cz/latkovani-obchod/no%C4%8Dn%C3%AD-aio-plenky/extra-save-aio-plienky-pul-patentky/farma-detail     -works

With turned of SEO the difference is only in virtuemart_category_id number:
http://www.plenkybobanek.cz/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=88&virtuemart_category_id=15&lang=cs
http://www.plenkybobanek.cz/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=88&virtuemart_category_id=28&lang=cs

Maybe the problem is not in different urls, but I need the same result for both pages

Any help appreciated, thank you and sorry for my bad english.

VirtueMart 3.2.2
Joomla! 3.6.0 Stable [ Noether ] 12-July-2016 21:14 GMT

[Ghost]

URL is actually found but you're getting a PHP error:

Call to a member function displayMediaThumb() on null

The issue is in your template overrides. Protostar works fine http://www.plenkybobanek.cz/latkovani-obchod/no%C4%8Dn%C3%AD-aio-plenky/farma-detail?template=protostar.

[hop]

Thank you for pointing me to right way. 
I have found this thread:
http://forum.virtuemart.net/index.php?topic=137497