Hi,
The coupon only works when it was apply on a product or on a category of products.
I have update HikaMarket on my side in order to manage coupon which does not have "filter". At this moment, the coupon is proportionality separated between the vendors depending on the product prices.
I can send you a pre-version by email with the modifications.
I submitted some modifications on HikaShop too for the HikaMarket compatibility, theses modification would be included in the next release (2.1.1).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.