Hi Bethofvt,
Thanks for contributing to our forum. There is currently a known technical problem that is causing the error message you mentioned here to be returned when searches are attempted from within the “Find Product” interface while anything other than "Keyword" is selected from the "Search By" drop down menu.
While we realize this behavior does not occur when listing directly through eBay, the root cause of this particular problem lies actually with the data we are receiving from eBay so we have opened a support case with eBay's Developer Support team to request that the problem be resolved.
However, in the mean time, you should still successfully be able to search by ISBN, title, author, or keyword through Auctiva's “Find Product” interface as long as you first select “Keyword” from the “Search By” drop down menu.
I hope this helps. If you need any further assistance with your account, please feel free to contact our customer support team by mousing over the “Help” tab within your account and selecting the “File Support Case” option.
-Mike