Global Products Not Displaying On Main site

I am using the simplemarket theme and marketpress plugin. I have the main site plus 4 subsites.
I have listed a product on one subsite and place a widget on the main site.
I am assuming that a global widget on the main site will display the sub site listings?
Unfortunately this isnt happening for me and I need someone to take a look at my set up and see if i am doing something wrong.