Cant' get marketpress to work on my network, need help.

Help!!! Okay, so I know I am not a programmer but I have had 2 programmers attempt to set the etsy style deal up on my site and they are both telling me that it's not working
Something to do with multisite and products and or navigation not working.

So I have a programmer testing in on a demo domain to see if it's a buddypress issue and still not working in network environment.

I am at a loss. seems simple enough from the videos. Here's all i want to do:

My users are "vendors" as in the sell at my downtown flea. I have them set up in Buddypress which I call FleaBook. These users are all approved by me first. Currently about 600 of them.

I thought we would simply add to each user ie, an option to create a store and then they would simply set it up. I have already set up my paypal api app which was approved for chained payments.

If you could give me some direction with this, it would be a good start.