Do you know the performance of that JV partner for other products? If he sent you the traffic, doesn't mean that it would convert. Maybe his list or promotion methods are not suitable for your kind of product. Of course, sometimes it looks like you are only the one 'guilty' for not successful JV, but I think you shouldn't blame yourself. JV just didn't work for your product. In this case it would be great if you could send a small thank-you gift to that JV partner for his efforts and thank him for participating. So next time you make a product launch that partner would still be interested to participate.

Have a nice day,
Egidijus