"Opportunity product revenue" record with no product name.

Does any of you know why an opportunity product revenue record where the field "Product Name" is not populated does not show up in the opportunity related section but shows up when I have a product name entered? Is this normal behavior? FYI if I run a report I find all my records even those with no product name. I tried thru workflow to update the field with a default one but it does not work either. It looks like you need to use the product selection eyeglass so that the product fields are populated (category, status, part ")
Thanks.