A potential buyer has to explicity change the search to include store inventory format items which is not very obvious.
The only time they would appear with default settings is if there were very few auction style listings that matched and you were in the top 5 or so sellers of that item.
Otherwise you need a few auction style items which are easily found by searches and include links to your eBay store to see all the others. They are more expensive to list that way but they attarct and redirect customers to your main stock.
