Virtuemart block purchase

[kailash.xantatech]

I have a requirement where i want to block purchase if two product in the cart are from different category. I tried putting category id and sending it when sending request but nothing helps, anyone has any idea. please help

joomla version - 3.4.8
VirtueMart 3.0.12

[jenkinhill]

http://forum.virtuemart.net/index.php?topic=79799.0
http://forum.virtuemart.net/index.php?topic=104795.0