This message will come up on the 'Product Screen' if your item is not found in the eBay catalogue when searching by barcode. Don't worry though, the eBay category linked to this product is searchable.
To search by title click the 'Sell Similar' link.
If the title search returns zero results your search term may be too specific, remove some of the keywords and try again.
If the search results still return zero results then you might have applied an incorrect profile to the product. For example if you apply a 'DVD' profile to a product, it must be a valid DVD product in order to be found on eBay as the search will only return results from eBay's DVD catalogue.