Dear Maria Pascual,
I'm very sorry that you are frustrated and that things don't just work for you. Which versions of VirtueMart and Joomla and PHP do you use on your server?
I have tried those rules with VirtueMart 2.x on Joomla 2 as well as with VirtueMart 3.x on Joomla 3, and both rules that you say make problems work just fine (check it out at
demo.open-tools.net/, user demo987, pw demo987, Select "Anguilla" as the country; Product
demo.open-tools.net/index.php?option=com...ory_id=15&Itemid=104 is from the category with your ID 470 (my category ID 15) ).
As a side note, I think in your third rule you want 0<=Weight-evaluate... rather than a strict <. Apart from that, I'm really impressed by your rule set!
Regaring the 500 Internal error message, I don't see any reason why that error should come from the rules, given that they work just fine for me. Do you have any PHP warnings or error message in your webserver's error log file?
Best regards,
Reinhold