need an expert who tells me how to attract sellers to my marketplace

Hello, I'm a webdesigner who tries to make his dream come true. I think i have a pretty good product, after 1 1/2 year of developing we are finally at the point where we can say "ok, lets invite sellers". The first The first feedback we got is: 60 invitiations, only 2 had a conversation with me on skype to talk about it. 1 of them said no, the other one is still thinking about it. Now i want to know, what should i do to get the first sellers on my platform? Only real experts needed!