schema confusion

I added the plugin hack to add more schema from schema.org – and it allowed adding to Category

however after creating a new listing for that category and then checking the listing on https://developers.google.com/structured-data/testing-tool/ no schema is being displayed

the category archive also does not show having schema. On another category changed schema to one used by default – and it doesn’t show either.

I went to some showcase sites and they are hit and miss showing schema – one wasn’t working another was at least showing default localbusiness

need some kind of explanation, walk through of how schema are supposed to work – at the moment not working at all