The main reason items don't show in search results is the search hasn't been updated.
The search works on an index to be as fast as possible.
We update the index every night (very early in the morning).
The down side to this is that items added today do not show in the search results until the next day.
Updating the index as items are added and removed and on demand are features in our roadmap.
To verify that the item is in the system you can search in the admin under Catalog > Items.